case study similar meaning

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What is another word for case study ?

Synonyms for case study case study, this thesaurus page includes all potential synonyms, words with the same meaning and similar terms for the word case study ., princeton's wordnet.

• case study noun

a careful study of some social unit (as a corporation or division within a corporation) that attempts to determine what factors led to its success or failure

a detailed analysis of a person or group from a social or psychological or medical point of view

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Concise Medical Dictionary, by Joseph C Segen, MD Rate these synonyms: 2.2 / 5 votes

Synonyms: Epidemiology Anecdotal report, anecdote, single case report

How to pronounce case study?

How to say case study in sign language, how to use case study in a sentence.

Josh Holmes :

For those asking, this is my response to West Virginia Roy Moore :' This clown is a walking, talking case study for the limitation of a prison's ability to rehabilitate,'.

Alba Pasini :

This case study is really important, since it testifies that a medical approach to maternal morbidity actually existed during the Lombard period, despite the rejection of the scientific progress which denoted all the Early Middle Age, also, it shows two rare findings, since post-mortem fetal extrusion is a quite rare phenomenon( especially in archaeological specimens), while only a few examples of trepanation are known for the European Early Middle Age.

Tesoro Corp :

We agree on the critical importance of continually learning from incidents and improving the safety of our operations, and inaccuracies in the case study do not detract from our resolve to learn from these incidents.

Sam Goodman :

The Hong Kong BNO scheme is an interesting case study of what can happen if there is political will, there are 12 welcome centers across the country and a really good support package which costs relatively little, including help with English language. And most importantly they just didn’t politicize it. All this has meant that 144,000 Hong Kongers have come here with little to no fuss, integrated quickly and there have been minimal issues.

Houston Astros :

I think I’m kind of a case study on this one.

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Case Study vs. Experiment: What's the Difference?

Key Differences

Comparison chart, generalization, preferred fields, case study and experiment definitions, when is a case study used, what is an experiment, how do case studies gather data, can case studies be generalized, what fields commonly use case studies, what type of data do experiments produce, can a case study include quantitative data, what is a case study, what is the main purpose of an experiment, is bias a concern in case studies, are experiments replicable, in which fields are experiments predominant, how do experiments impact scientific knowledge, what is a longitudinal case study, can experiments be conducted in natural settings, what is the role of control in experiments, how long can a case study last, what ethical considerations are involved in experiments, can case studies be used to test hypotheses, how is replicability ensured in experiments.

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Case Study Research Method in Psychology

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

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Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

On This Page:

Case studies are in-depth investigations of a person, group, event, or community. Typically, data is gathered from various sources using several methods (e.g., observations & interviews).

The case study research method originated in clinical medicine (the case history, i.e., the patient’s personal history). In psychology, case studies are often confined to the study of a particular individual.

The information is mainly biographical and relates to events in the individual’s past (i.e., retrospective), as well as to significant events that are currently occurring in his or her everyday life.

The case study is not a research method, but researchers select methods of data collection and analysis that will generate material suitable for case studies.

Freud (1909a, 1909b) conducted very detailed investigations into the private lives of his patients in an attempt to both understand and help them overcome their illnesses.

This makes it clear that the case study is a method that should only be used by a psychologist, therapist, or psychiatrist, i.e., someone with a professional qualification.

There is an ethical issue of competence. Only someone qualified to diagnose and treat a person can conduct a formal case study relating to atypical (i.e., abnormal) behavior or atypical development.

 Famous Case Studies

• Anna O – One of the most famous case studies, documenting psychoanalyst Josef Breuer’s treatment of “Anna O” (real name Bertha Pappenheim) for hysteria in the late 1800s using early psychoanalytic theory.
• Little Hans – A child psychoanalysis case study published by Sigmund Freud in 1909 analyzing his five-year-old patient Herbert Graf’s house phobia as related to the Oedipus complex.
• Bruce/Brenda – Gender identity case of the boy (Bruce) whose botched circumcision led psychologist John Money to advise gender reassignment and raise him as a girl (Brenda) in the 1960s.
• Genie Wiley – Linguistics/psychological development case of the victim of extreme isolation abuse who was studied in 1970s California for effects of early language deprivation on acquiring speech later in life.
• Phineas Gage – One of the most famous neuropsychology case studies analyzes personality changes in railroad worker Phineas Gage after an 1848 brain injury involving a tamping iron piercing his skull.

Clinical Case Studies

• Studying the effectiveness of psychotherapy approaches with an individual patient
• Assessing and treating mental illnesses like depression, anxiety disorders, PTSD
• Neuropsychological cases investigating brain injuries or disorders

Child Psychology Case Studies

• Studying psychological development from birth through adolescence
• Cases of learning disabilities, autism spectrum disorders, ADHD
• Effects of trauma, abuse, deprivation on development

Types of Case Studies

• Explanatory case studies : Used to explore causation in order to find underlying principles. Helpful for doing qualitative analysis to explain presumed causal links.
• Exploratory case studies : Used to explore situations where an intervention being evaluated has no clear set of outcomes. It helps define questions and hypotheses for future research.
• Descriptive case studies : Describe an intervention or phenomenon and the real-life context in which it occurred. It is helpful for illustrating certain topics within an evaluation.
• Multiple-case studies : Used to explore differences between cases and replicate findings across cases. Helpful for comparing and contrasting specific cases.
• Intrinsic : Used to gain a better understanding of a particular case. Helpful for capturing the complexity of a single case.
• Collective : Used to explore a general phenomenon using multiple case studies. Helpful for jointly studying a group of cases in order to inquire into the phenomenon.

Where Do You Find Data for a Case Study?

There are several places to find data for a case study. The key is to gather data from multiple sources to get a complete picture of the case and corroborate facts or findings through triangulation of evidence. Most of this information is likely qualitative (i.e., verbal description rather than measurement), but the psychologist might also collect numerical data.

1. Primary sources

• Interviews – Interviewing key people related to the case to get their perspectives and insights. The interview is an extremely effective procedure for obtaining information about an individual, and it may be used to collect comments from the person’s friends, parents, employer, workmates, and others who have a good knowledge of the person, as well as to obtain facts from the person him or herself.
• Observations – Observing behaviors, interactions, processes, etc., related to the case as they unfold in real-time.
• Documents & Records – Reviewing private documents, diaries, public records, correspondence, meeting minutes, etc., relevant to the case.

2. Secondary sources

• News/Media – News coverage of events related to the case study.
• Academic articles – Journal articles, dissertations etc. that discuss the case.
• Government reports – Official data and records related to the case context.
• Books/films – Books, documentaries or films discussing the case.

3. Archival records

Searching historical archives, museum collections and databases to find relevant documents, visual/audio records related to the case history and context.

Public archives like newspapers, organizational records, photographic collections could all include potentially relevant pieces of information to shed light on attitudes, cultural perspectives, common practices and historical contexts related to psychology.

4. Organizational records

Organizational records offer the advantage of often having large datasets collected over time that can reveal or confirm psychological insights.

Of course, privacy and ethical concerns regarding confidential data must be navigated carefully.

However, with proper protocols, organizational records can provide invaluable context and empirical depth to qualitative case studies exploring the intersection of psychology and organizations.

• Organizational/industrial psychology research : Organizational records like employee surveys, turnover/retention data, policies, incident reports etc. may provide insight into topics like job satisfaction, workplace culture and dynamics, leadership issues, employee behaviors etc.
• Clinical psychology : Therapists/hospitals may grant access to anonymized medical records to study aspects like assessments, diagnoses, treatment plans etc. This could shed light on clinical practices.
• School psychology : Studies could utilize anonymized student records like test scores, grades, disciplinary issues, and counseling referrals to study child development, learning barriers, effectiveness of support programs, and more.

How do I Write a Case Study in Psychology?

Follow specified case study guidelines provided by a journal or your psychology tutor. General components of clinical case studies include: background, symptoms, assessments, diagnosis, treatment, and outcomes. Interpreting the information means the researcher decides what to include or leave out. A good case study should always clarify which information is the factual description and which is an inference or the researcher’s opinion.

1. Introduction

• Provide background on the case context and why it is of interest, presenting background information like demographics, relevant history, and presenting problem.
• Compare briefly to similar published cases if applicable. Clearly state the focus/importance of the case.

2. Case Presentation

• Describe the presenting problem in detail, including symptoms, duration,and impact on daily life.
• Include client demographics like age and gender, information about social relationships, and mental health history.
• Describe all physical, emotional, and/or sensory symptoms reported by the client.
• Use patient quotes to describe the initial complaint verbatim. Follow with full-sentence summaries of relevant history details gathered, including key components that led to a working diagnosis.
• Summarize clinical exam results, namely orthopedic/neurological tests, imaging, lab tests, etc. Note actual results rather than subjective conclusions. Provide images if clearly reproducible/anonymized.
• Clearly state the working diagnosis or clinical impression before transitioning to management.

3. Management and Outcome

• Indicate the total duration of care and number of treatments given over what timeframe. Use specific names/descriptions for any therapies/interventions applied.
• Present the results of the intervention,including any quantitative or qualitative data collected.
• For outcomes, utilize visual analog scales for pain, medication usage logs, etc., if possible. Include patient self-reports of improvement/worsening of symptoms. Note the reason for discharge/end of care.

4. Discussion

• Analyze the case, exploring contributing factors, limitations of the study, and connections to existing research.
• Analyze the effectiveness of the intervention,considering factors like participant adherence, limitations of the study, and potential alternative explanations for the results.
• Identify any questions raised in the case analysis and relate insights to established theories and current research if applicable. Avoid definitive claims about physiological explanations.
• Offer clinical implications, and suggest future research directions.

5. Additional Items

• Thank specific assistants for writing support only. No patient acknowledgments.
• References should directly support any key claims or quotes included.
• Use tables/figures/images only if substantially informative. Include permissions and legends/explanatory notes.
• Provides detailed (rich qualitative) information.
• Provides insight for further research.
• Permitting investigation of otherwise impractical (or unethical) situations.

Case studies allow a researcher to investigate a topic in far more detail than might be possible if they were trying to deal with a large number of research participants (nomothetic approach) with the aim of ‘averaging’.

Because of their in-depth, multi-sided approach, case studies often shed light on aspects of human thinking and behavior that would be unethical or impractical to study in other ways.

Research that only looks into the measurable aspects of human behavior is not likely to give us insights into the subjective dimension of experience, which is important to psychoanalytic and humanistic psychologists.

Case studies are often used in exploratory research. They can help us generate new ideas (that might be tested by other methods). They are an important way of illustrating theories and can help show how different aspects of a person’s life are related to each other.

The method is, therefore, important for psychologists who adopt a holistic point of view (i.e., humanistic psychologists ).

Limitations

• Lacking scientific rigor and providing little basis for generalization of results to the wider population.
• Researchers’ own subjective feelings may influence the case study (researcher bias).
• Difficult to replicate.
• Time-consuming and expensive.
• The volume of data, together with the time restrictions in place, impacted the depth of analysis that was possible within the available resources.

Because a case study deals with only one person/event/group, we can never be sure if the case study investigated is representative of the wider body of “similar” instances. This means the conclusions drawn from a particular case may not be transferable to other settings.

Because case studies are based on the analysis of qualitative (i.e., descriptive) data , a lot depends on the psychologist’s interpretation of the information she has acquired.

This means that there is a lot of scope for Anna O , and it could be that the subjective opinions of the psychologist intrude in the assessment of what the data means.

For example, Freud has been criticized for producing case studies in which the information was sometimes distorted to fit particular behavioral theories (e.g., Little Hans ).

This is also true of Money’s interpretation of the Bruce/Brenda case study (Diamond, 1997) when he ignored evidence that went against his theory.

Breuer, J., & Freud, S. (1895).  Studies on hysteria . Standard Edition 2: London.

Curtiss, S. (1981). Genie: The case of a modern wild child .

Diamond, M., & Sigmundson, K. (1997). Sex Reassignment at Birth: Long-term Review and Clinical Implications. Archives of Pediatrics & Adolescent Medicine , 151(3), 298-304

Freud, S. (1909a). Analysis of a phobia of a five year old boy. In The Pelican Freud Library (1977), Vol 8, Case Histories 1, pages 169-306

Freud, S. (1909b). Bemerkungen über einen Fall von Zwangsneurose (Der “Rattenmann”). Jb. psychoanal. psychopathol. Forsch ., I, p. 357-421; GW, VII, p. 379-463; Notes upon a case of obsessional neurosis, SE , 10: 151-318.

Harlow J. M. (1848). Passage of an iron rod through the head.  Boston Medical and Surgical Journal, 39 , 389–393.

Harlow, J. M. (1868).  Recovery from the Passage of an Iron Bar through the Head .  Publications of the Massachusetts Medical Society. 2  (3), 327-347.

Money, J., & Ehrhardt, A. A. (1972).  Man & Woman, Boy & Girl : The Differentiation and Dimorphism of Gender Identity from Conception to Maturity. Baltimore, Maryland: Johns Hopkins University Press.

Money, J., & Tucker, P. (1975). Sexual signatures: On being a man or a woman.

Further Information

• Case Study Approach
• Case Study Method
• Enhancing the Quality of Case Studies in Health Services Research
• “We do things together” A case study of “couplehood” in dementia
• Using mixed methods for evaluating an integrative approach to cancer care: a case study

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Some of the distinct Similarities and Key Differences between Case Study and Historical Research Design?

Both case study and historical research design share qualitative methodologies that involve in-depth exploration and a contextual understanding of their subjects. They both employ rich data collection methods, emphasizing the importance of holistic perspectives and participant-centered approaches.

However, key differences arise in their temporal focus and scope. Case studies typically concentrate on present or recent instances, providing detailed insights into specific cases, while historical research design spans a longer time frame, examining historical events and trends with a broader contextual lens.

The unit of analysis also varies, with case studies focusing on individual cases and historical research analyzing events and developments over time. While both contribute to a nuanced understanding of their subjects, case studies tend to yield practical insights for immediate application, whereas historical research design contributes to a broader understanding of historical processes. Both methodologies prioritize the unique characteristics of their subjects, whether a specific case or historical events, and involve an interpretive process to derive meaning.

However, key differences lie in their temporal dimensions and scope; case studies focus on the present or recent past with a narrow scope, analyzing specific instances, while historical research design spans a longer time frame, addressing broader historical events and developments. The unit of analysis differs, with case studies examining a specific case, and historical research considering historical events and their implications. Additionally, the purposes diverge, as case studies aim for practical insights, while historical research contributes to a broader understanding of historical processes with potential generalizability.

These distinctions underscore the nuanced applications of each approach in research contexts. In this blog post, we highlight some of the apparent similarities and key differences between case study and historical research design. But first of all, let us discuss some of the obvious similarities between the two research designs.

Similarities between Case Study and Historical Research Design

• Both case study and historical research design are qualitative research methods. They involve in-depth analysis and interpretation of data to gain a nuanced understanding of the subject matter.
• Both methodologies often involve the collection of rich and detailed data. This can include sources such as documents, artifacts, interviews, and observations, allowing for a comprehensive exploration of the subject.
• Both approaches emphasize the importance of context in understanding the phenomena under investigation. Case studies consider the real-life context of a specific instance, while historical research delves into the historical context surrounding events and developments.
• Both case study and historical research take a holistic perspective. They aim to provide a comprehensive understanding of the subject, considering various aspects, relationships, and influences.
• Both methodologies involve an in-depth exploration of the subject matter. Case studies seek to provide a detailed examination of a particular case, while historical research aims to understand events and their significance over time.
• Both approaches often require the analysis of multiple data sources. Researchers in case studies and historical research may examine various documents, artifacts, and other forms of evidence to construct a detailed narrative.
• Both methodologies often focus on specificity. Case studies delve into a particular instance or bounded system, while historical research aims to understand specific historical events and their impact.
• Both case study and historical research involve an interpretive process. Researchers analyze and interpret the data to derive meaning and insights, recognizing the subjective nature of their interpretations.
• Both methodologies have the potential to contribute to theoretical understanding. Case studies may generate insights applicable to broader contexts, and historical research can contribute to the development of historical theories or perspectives.
• Unique contextualization:
• Both approaches involve the unique contextualization of the subject matter. Case studies contextualize a specific instance within its real-world setting, while historical research contextualizes events within the historical period in which they occurred.

Understanding these similarities can help researchers appreciate the commonalities in their qualitative approaches and adapt their methods accordingly, depending on whether they are conducting a case study or historical research.

Case studies and historical research design differ primarily in their focus and scope. While historical research design adopts an observational stance, contributing to theoretical perspectives and a comprehensive understanding of historical phenomena, the unit of analysis also varies, a great deal with case studies.  These distinctions highlight the nuanced applications of each approach in research contexts.  In the next section of this write-up, we discuss key differences between case study and historical research design

Key differences between Case Study and Historical Research Design

• Case Study: Primarily focuses on the present or recent past, examining a specific instance or bounded system within its current or recent context.
• Historical Research Design: Focuses on the past, exploring events, developments, and phenomena within a historical context, often involving a longitudinal perspective.
• Case Study: Typically has a narrower scope, concentrating on a specific case or bounded system to provide an in-depth understanding.
• Historical Research Design: Encompasses a broader scope, aiming to understand historical events, trends, and their implications over a longer period.
• Case Study: The unit of analysis is the specific case itself, which could be an individual, a group, an organization, or a community.
• Historical Research Design: The unit of analysis is historical events, periods, or developments, often involving a broader societal or contextual focus.
• Case Study: Aims to provide a detailed understanding of a specific instance, often to inform practical applications or interventions.
• Historical Research Design: Aims to explore and understand historical events, patterns, and trends for the sake of knowledge and understanding historical processes.
• Case Study: Generalization is typically not the primary goal, as the emphasis is on the unique aspects of the specific case.
• Historical Research Design: Seeks to draw generalizable conclusions about historical trends, events, or phenomena, contributing to a broader understanding of historical processes.
• Case Study: Involves an in-depth examination of the specific case, often through pattern recognition and exploration of relationships within the case.
• Historical Research Design: Involves analysis of historical documents, artifacts, and evidence to construct a narrative or interpretation of historical events and their significance.
• Case Study: Typically has a more immediate or short-term temporal perspective, focusing on recent or current events.
• Historical Research Design: Requires a longer-term temporal perspective, examining events and developments over an extended period in the past.
• Case Study: The researcher often plays an active role, engaging with the case and collecting multiple forms of data.
• Historical Research Design: The researcher adopts a more observational and interpretive role, analyzing historical documents and evidence to construct a narrative.
• Case Study: Findings may have direct implications for the specific case or similar cases in similar contexts.
• Historical Research Design: Findings contribute to a broader historical understanding and may inform our knowledge of historical processes, but the direct applicability to present situations may vary.
• Case Study: May contribute to theory development, especially when patterns observed in the case have broader implications.
• Historical Research Design: Can contribute to the development of historical theories or perspectives, providing insights into the dynamics of historical events.

Both case study and historical research design are valuable tools for gaining insights into complex issues. The choice of which design to use depends on the specific research question and the available data. Understanding these key similarities and differences helps researchers choose the most appropriate approach based on their research objectives and the nature of the subject matter.

Dr Syed Hafeez Ahmad

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Home » Case Study – Methods, Examples and Guide

Case Study – Methods, Examples and Guide

Table of Contents

A case study is a research method that involves an in-depth examination and analysis of a particular phenomenon or case, such as an individual, organization, community, event, or situation.

It is a qualitative research approach that aims to provide a detailed and comprehensive understanding of the case being studied. Case studies typically involve multiple sources of data, including interviews, observations, documents, and artifacts, which are analyzed using various techniques, such as content analysis, thematic analysis, and grounded theory. The findings of a case study are often used to develop theories, inform policy or practice, or generate new research questions.

Types of Case Study

Types and Methods of Case Study are as follows:

Single-Case Study

A single-case study is an in-depth analysis of a single case. This type of case study is useful when the researcher wants to understand a specific phenomenon in detail.

For Example , A researcher might conduct a single-case study on a particular individual to understand their experiences with a particular health condition or a specific organization to explore their management practices. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of a single-case study are often used to generate new research questions, develop theories, or inform policy or practice.

Multiple-Case Study

A multiple-case study involves the analysis of several cases that are similar in nature. This type of case study is useful when the researcher wants to identify similarities and differences between the cases.

For Example, a researcher might conduct a multiple-case study on several companies to explore the factors that contribute to their success or failure. The researcher collects data from each case, compares and contrasts the findings, and uses various techniques to analyze the data, such as comparative analysis or pattern-matching. The findings of a multiple-case study can be used to develop theories, inform policy or practice, or generate new research questions.

Exploratory Case Study

An exploratory case study is used to explore a new or understudied phenomenon. This type of case study is useful when the researcher wants to generate hypotheses or theories about the phenomenon.

For Example, a researcher might conduct an exploratory case study on a new technology to understand its potential impact on society. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as grounded theory or content analysis. The findings of an exploratory case study can be used to generate new research questions, develop theories, or inform policy or practice.

Descriptive Case Study

A descriptive case study is used to describe a particular phenomenon in detail. This type of case study is useful when the researcher wants to provide a comprehensive account of the phenomenon.

For Example, a researcher might conduct a descriptive case study on a particular community to understand its social and economic characteristics. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of a descriptive case study can be used to inform policy or practice or generate new research questions.

Instrumental Case Study

An instrumental case study is used to understand a particular phenomenon that is instrumental in achieving a particular goal. This type of case study is useful when the researcher wants to understand the role of the phenomenon in achieving the goal.

For Example, a researcher might conduct an instrumental case study on a particular policy to understand its impact on achieving a particular goal, such as reducing poverty. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of an instrumental case study can be used to inform policy or practice or generate new research questions.

Case Study Data Collection Methods

Here are some common data collection methods for case studies:

Interviews involve asking questions to individuals who have knowledge or experience relevant to the case study. Interviews can be structured (where the same questions are asked to all participants) or unstructured (where the interviewer follows up on the responses with further questions). Interviews can be conducted in person, over the phone, or through video conferencing.

Observations

Observations involve watching and recording the behavior and activities of individuals or groups relevant to the case study. Observations can be participant (where the researcher actively participates in the activities) or non-participant (where the researcher observes from a distance). Observations can be recorded using notes, audio or video recordings, or photographs.

Documents can be used as a source of information for case studies. Documents can include reports, memos, emails, letters, and other written materials related to the case study. Documents can be collected from the case study participants or from public sources.

Surveys involve asking a set of questions to a sample of individuals relevant to the case study. Surveys can be administered in person, over the phone, through mail or email, or online. Surveys can be used to gather information on attitudes, opinions, or behaviors related to the case study.

Artifacts are physical objects relevant to the case study. Artifacts can include tools, equipment, products, or other objects that provide insights into the case study phenomenon.

How to conduct Case Study Research

Conducting a case study research involves several steps that need to be followed to ensure the quality and rigor of the study. Here are the steps to conduct case study research:

• Define the research questions: The first step in conducting a case study research is to define the research questions. The research questions should be specific, measurable, and relevant to the case study phenomenon under investigation.
• Select the case: The next step is to select the case or cases to be studied. The case should be relevant to the research questions and should provide rich and diverse data that can be used to answer the research questions.
• Collect data: Data can be collected using various methods, such as interviews, observations, documents, surveys, and artifacts. The data collection method should be selected based on the research questions and the nature of the case study phenomenon.
• Analyze the data: The data collected from the case study should be analyzed using various techniques, such as content analysis, thematic analysis, or grounded theory. The analysis should be guided by the research questions and should aim to provide insights and conclusions relevant to the research questions.
• Draw conclusions: The conclusions drawn from the case study should be based on the data analysis and should be relevant to the research questions. The conclusions should be supported by evidence and should be clearly stated.
• Validate the findings: The findings of the case study should be validated by reviewing the data and the analysis with participants or other experts in the field. This helps to ensure the validity and reliability of the findings.
• Write the report: The final step is to write the report of the case study research. The report should provide a clear description of the case study phenomenon, the research questions, the data collection methods, the data analysis, the findings, and the conclusions. The report should be written in a clear and concise manner and should follow the guidelines for academic writing.

Examples of Case Study

Here are some examples of case study research:

• The Hawthorne Studies : Conducted between 1924 and 1932, the Hawthorne Studies were a series of case studies conducted by Elton Mayo and his colleagues to examine the impact of work environment on employee productivity. The studies were conducted at the Hawthorne Works plant of the Western Electric Company in Chicago and included interviews, observations, and experiments.
• The Stanford Prison Experiment: Conducted in 1971, the Stanford Prison Experiment was a case study conducted by Philip Zimbardo to examine the psychological effects of power and authority. The study involved simulating a prison environment and assigning participants to the role of guards or prisoners. The study was controversial due to the ethical issues it raised.
• The Challenger Disaster: The Challenger Disaster was a case study conducted to examine the causes of the Space Shuttle Challenger explosion in 1986. The study included interviews, observations, and analysis of data to identify the technical, organizational, and cultural factors that contributed to the disaster.
• The Enron Scandal: The Enron Scandal was a case study conducted to examine the causes of the Enron Corporation’s bankruptcy in 2001. The study included interviews, analysis of financial data, and review of documents to identify the accounting practices, corporate culture, and ethical issues that led to the company’s downfall.
• The Fukushima Nuclear Disaster : The Fukushima Nuclear Disaster was a case study conducted to examine the causes of the nuclear accident that occurred at the Fukushima Daiichi Nuclear Power Plant in Japan in 2011. The study included interviews, analysis of data, and review of documents to identify the technical, organizational, and cultural factors that contributed to the disaster.

Application of Case Study

Case studies have a wide range of applications across various fields and industries. Here are some examples:

Business and Management

Case studies are widely used in business and management to examine real-life situations and develop problem-solving skills. Case studies can help students and professionals to develop a deep understanding of business concepts, theories, and best practices.

Case studies are used in healthcare to examine patient care, treatment options, and outcomes. Case studies can help healthcare professionals to develop critical thinking skills, diagnose complex medical conditions, and develop effective treatment plans.

Case studies are used in education to examine teaching and learning practices. Case studies can help educators to develop effective teaching strategies, evaluate student progress, and identify areas for improvement.

Social Sciences

Case studies are widely used in social sciences to examine human behavior, social phenomena, and cultural practices. Case studies can help researchers to develop theories, test hypotheses, and gain insights into complex social issues.

Law and Ethics

Case studies are used in law and ethics to examine legal and ethical dilemmas. Case studies can help lawyers, policymakers, and ethical professionals to develop critical thinking skills, analyze complex cases, and make informed decisions.

Purpose of Case Study

The purpose of a case study is to provide a detailed analysis of a specific phenomenon, issue, or problem in its real-life context. A case study is a qualitative research method that involves the in-depth exploration and analysis of a particular case, which can be an individual, group, organization, event, or community.

The primary purpose of a case study is to generate a comprehensive and nuanced understanding of the case, including its history, context, and dynamics. Case studies can help researchers to identify and examine the underlying factors, processes, and mechanisms that contribute to the case and its outcomes. This can help to develop a more accurate and detailed understanding of the case, which can inform future research, practice, or policy.

Case studies can also serve other purposes, including:

• Illustrating a theory or concept: Case studies can be used to illustrate and explain theoretical concepts and frameworks, providing concrete examples of how they can be applied in real-life situations.
• Developing hypotheses: Case studies can help to generate hypotheses about the causal relationships between different factors and outcomes, which can be tested through further research.
• Providing insight into complex issues: Case studies can provide insights into complex and multifaceted issues, which may be difficult to understand through other research methods.
• Informing practice or policy: Case studies can be used to inform practice or policy by identifying best practices, lessons learned, or areas for improvement.

Advantages of Case Study Research

There are several advantages of case study research, including:

• In-depth exploration: Case study research allows for a detailed exploration and analysis of a specific phenomenon, issue, or problem in its real-life context. This can provide a comprehensive understanding of the case and its dynamics, which may not be possible through other research methods.
• Rich data: Case study research can generate rich and detailed data, including qualitative data such as interviews, observations, and documents. This can provide a nuanced understanding of the case and its complexity.
• Holistic perspective: Case study research allows for a holistic perspective of the case, taking into account the various factors, processes, and mechanisms that contribute to the case and its outcomes. This can help to develop a more accurate and comprehensive understanding of the case.
• Theory development: Case study research can help to develop and refine theories and concepts by providing empirical evidence and concrete examples of how they can be applied in real-life situations.
• Practical application: Case study research can inform practice or policy by identifying best practices, lessons learned, or areas for improvement.
• Contextualization: Case study research takes into account the specific context in which the case is situated, which can help to understand how the case is influenced by the social, cultural, and historical factors of its environment.

Limitations of Case Study Research

There are several limitations of case study research, including:

• Limited generalizability : Case studies are typically focused on a single case or a small number of cases, which limits the generalizability of the findings. The unique characteristics of the case may not be applicable to other contexts or populations, which may limit the external validity of the research.
• Biased sampling: Case studies may rely on purposive or convenience sampling, which can introduce bias into the sample selection process. This may limit the representativeness of the sample and the generalizability of the findings.
• Subjectivity: Case studies rely on the interpretation of the researcher, which can introduce subjectivity into the analysis. The researcher’s own biases, assumptions, and perspectives may influence the findings, which may limit the objectivity of the research.
• Limited control: Case studies are typically conducted in naturalistic settings, which limits the control that the researcher has over the environment and the variables being studied. This may limit the ability to establish causal relationships between variables.
• Time-consuming: Case studies can be time-consuming to conduct, as they typically involve a detailed exploration and analysis of a specific case. This may limit the feasibility of conducting multiple case studies or conducting case studies in a timely manner.
• Resource-intensive: Case studies may require significant resources, including time, funding, and expertise. This may limit the ability of researchers to conduct case studies in resource-constrained settings.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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How a Case Study Differs from Other Types of Research

When it comes to research, there are a variety of methods used to acquire data and draw conclusions. Among them is the case study, which looks in depth at a single event or individual to gain insight into broader trends. But how does this approach differ from other types of research? In this blog post, we’ll explore the distinctions between case studies and other types of research — such as surveys and experiments — so that you can decide which method is best for your project.

Let’s start by defining what a case study is. A case study is an in-depth look at a specific event, person or situation in order to draw conclusions about broader trends or issues. It involves collecting qualitative (e.g., interviews) and quantitative (e.g., surveys) data from multiple sources and analyzing it to form an argument or hypothesis. Unlike some other types of research, case studies are not necessarily intended to be generalizable; rather, they are meant to provide insight into the particular subject being studied.

Case studies differ from other types of research in several ways:

They rely heavily on qualitative data: As mentioned above, one key distinction between a case study and other forms of research is that it relies heavily on qualitative data — such as interviews — rather than quantitative data like surveys or experiments. Qualitative data provides deeper insight into the subject being studied by delving into its complexities and nuances, which can often be missed by more structured forms of data collection like surveys or experiments.

They focus on a single event/person/situation: Another distinguishing feature of case studies is that they focus on studying one particular event/person/situation in depth rather than attempting to draw broad generalizations from multiple sources or cases. This allows researchers to gain insight into the dynamics at play within the particular context being studied, rather than attempting to make larger claims about similar events in different contexts without adequate evidence to support them.

They may not be generalizable: Finally, unlike some other forms of research that seek generalizable results applicable across multiple contexts (e.g., survey results), case studies may not necessarily have generalizability as their primary goal; instead, they seek deeper understanding through exploring details within the single context being studied itself.

When a case study is the best approach

Now that we’ve looked at what distinguishes a case study from other types of research let’s consider when it might be most appropriate for your project needs:

When you need an in-depth understanding: Case studies are particularly well suited for projects where an in-depth understanding of an individual person/event/situation is needed rather than broad generalizations about similar events across multiple contexts. For example, if you were researching how people interact with technology and wanted greater insight into how different users interact with specific software applications then conducting several detailed interviews with users would likely yield better results than conducting a survey across multiple populations where responses might be more generic due to lack of personal detail involved with each response given by participants .

When you need contextual information: Case studies are also useful when considering complex situations where contextual information may influence outcomes; for example if you wanted to understand how poverty affects access to education then looking at individual stories within certain communities could provide valuable insights that would otherwise be missed if only considering survey responses from those communities without any further exploration through interviews etc..

When you need rich narrative detail: Finally, if your project requires rich narrative detail — such as stories about peoples lives — then again conducting several detailed interviews would likely yield better results than simply surveying participants as these kinds of stories may not always come out through standard survey questions alone due to lack of personal engagement involved with completing them accurately etc.

In conclusion then while there are many similarities between various forms of research there are also important distinctions between them too – particularly when comparing something like a case study against something like surveys or experiments etc.. The key takeaway here though should be when deciding which method best suits your project needs consider carefully whether getting an ‘in-depth understanding’ , ‘contextual information’ , ‘rich narrative detail’ etc..are primary goals – then use this knowledge alongside others factors such as time available , budget constraints etc..to decide which method best fits your requirements overall .

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Long COVID or Post-COVID Conditions

Some people who have been infected with the virus that causes COVID-19 can experience long-term effects from their infection, known as Long COVID or Post-COVID Conditions (PCC). Long COVID is broadly defined as signs, symptoms, and conditions that continue or develop after acute COVID-19 infection. This definition  of Long COVID was developed by the Department of Health and Human Services (HHS) in collaboration with CDC and other partners.

People call Long COVID by many names, including Post-COVID Conditions, long-haul COVID, post-acute COVID-19, long-term effects of COVID, and chronic COVID. The term post-acute sequelae of SARS CoV-2 infection (PASC) is also used to refer to a subset of Long COVID.

What You Need to Know

• Long COVID is a real illness and can result in chronic conditions that require comprehensive care. There are resources available .
• Long COVID can include a wide range of ongoing health problems; these conditions can last weeks, months, or years.
• Long COVID occurs more often in people who had severe COVID-19 illness, but anyone who has been infected with the virus that causes COVID-19 can experience it.
• People who are not vaccinated against COVID-19 and become infected may have a higher risk of developing Long COVID compared to people who have been vaccinated.
• People can be reinfected with SARS-CoV-2, the virus that causes COVID-19, multiple times. Each time a person is infected or reinfected with SARS-CoV-2, they have a risk of developing Long COVID.
• While most people with Long COVID have evidence of infection or COVID-19 illness, in some cases, a person with Long COVID may not have tested positive for the virus or known they were infected.
• CDC and partners are working to understand more about who experiences Long COVID and why, including whether groups disproportionately impacted by COVID-19 are at higher risk.

In July 2021, Long COVID was added as a recognized condition that could result in a disability under the Americans with Disabilities Act (ADA). Learn more: Guidance on “Long COVID” as a Disability Under the ADA .

About Long COVID

Long COVID is a wide range of new, returning, or ongoing health problems that people experience after being infected with the virus that causes COVID-19. Most people with COVID-19 get better within a few days to a few weeks after infection, so at least 4 weeks after infection is the start of when Long COVID could first be identified. Anyone who was infected can experience Long COVID. Most people with Long COVID experienced symptoms days after first learning they had COVID-19, but some people who later experienced Long COVID did not know when they got infected.

There is no test that determines if your symptoms or condition is due to COVID-19. Long COVID is not one illness. Your healthcare provider considers a diagnosis of Long COVID based on your health history, including if you had a diagnosis of COVID-19 either by a positive test or by symptoms or exposure, as well as based on a health examination.

Science behind Long COVID

RECOVER: Researching COVID to Enhance Recovery

People with Long COVID may experience many symptoms.

People with Long COVID can have a wide range of symptoms that can last weeks, months, or even years after infection. Sometimes the symptoms can even go away and come back again. For some people, Long COVID can last weeks, months, or years after COVID-19 illness and can sometimes result in disability.

Long COVID may not affect everyone the same way. People with Long COVID may experience health problems from different types and combinations of symptoms that may emerge, persist, resolve, and reemerge over different lengths of time. Though most patients’ symptoms slowly improve with time, speaking with your healthcare provider about the symptoms you are experiencing after having COVID-19 could help determine if you might have Long COVID.

People who experience Long COVID most commonly report:

General symptoms ( Not a Comprehensive List)

• Tiredness or fatigue that interferes with daily life
• Symptoms that get worse after physical or mental effort (also known as “ post-exertional malaise ”)

Respiratory and heart symptoms

• Difficulty breathing or shortness of breath
• Fast-beating or pounding heart (also known as heart palpitations)

Neurological symptoms

• Difficulty thinking or concentrating (sometimes referred to as “brain fog”)
• Sleep problems
• Dizziness when you stand up (lightheadedness)
• Pins-and-needles feelings
• Change in smell or taste
• Depression or anxiety

Digestive symptoms

• Stomach pain

Other symptoms

• Joint or muscle pain
• Changes in menstrual cycles

Symptoms that are hard to explain and manage

Some people with Long COVID have symptoms that are not explained by tests or easy to manage.

People with Long COVID may develop or continue to have symptoms that are hard to explain and manage. Clinical evaluations and results of routine blood tests, chest X-rays, and electrocardiograms may be normal. The symptoms are similar to those reported by people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and other poorly understood chronic illnesses that may occur after other infections. People with these unexplained symptoms may be misunderstood by their healthcare providers, which can result in a delay in diagnosis and receiving the appropriate care or treatment.

Review these tips to help prepare for a healthcare provider appointment for Long COVID.

Health conditions

Some people experience new health conditions after COVID-19 illness.

Some people, especially those who had severe COVID-19, experience multiorgan effects or autoimmune conditions with symptoms lasting weeks, months, or even years after COVID-19 illness. Multi-organ effects can involve many body systems, including the heart, lung, kidney, skin, and brain. As a result of these effects, people who have had COVID-19 may be more likely to develop new health conditions such as diabetes, heart conditions, blood clots, or neurological conditions compared with people who have not had COVID-19.

People experiencing any severe illness may develop health problems

People experiencing any severe illness, hospitalization, or treatment may develop problems such as post-intensive care syndrome (PICS).

PICS refers to the health effects that may begin when a person is in an intensive care unit (ICU), and which may persist after a person returns home. These effects can include muscle weakness, problems with thinking and judgment, and symptoms of post-traumatic stress disorder  (PTSD), a long-term reaction to a very stressful event. While PICS is not specific to infection with SARS-CoV-2, it may occur and contribute to the person’s experience of Long COVID. For people who experience PICS following a COVID-19 diagnosis, it is difficult to determine whether these health problems are caused by a severe illness, the virus itself, or a combination of both.

People More Likely to Develop Long COVID

Some people may be more at risk for developing Long COVID.

Researchers are working to understand which people or groups of people are more likely to have Long COVID, and why. Studies have shown that some groups of people may be affected more by Long COVID. These are examples and not a comprehensive list of people or groups who might be more at risk than other groups for developing Long COVID:

• People who have experienced more severe COVID-19 illness, especially those who were hospitalized or needed intensive care.
• People who had underlying health conditions prior to COVID-19.
• People who did not get a COVID-19 vaccine.

Health Inequities May Affect Populations at Risk for Long COVID

Some people are at increased risk of getting sick from COVID-19 because of where they live or work, or because they can’t get health care. Health inequities may put some people from racial or ethnic minority groups and some people with disabilities at greater risk for developing Long COVID. Scientists are researching some of those factors that may place these communities at higher risk of getting infected or developing Long COVID.

Preventing Long COVID

The best way to prevent Long COVID is to protect yourself and others from becoming infected. For people who are eligible, CDC recommends staying up to date on COVID-19 vaccination , along with improving ventilation, getting tested for COVID-19 if needed, and seeking treatment for COVID-19 if eligible. Additional preventative measures include avoiding close contact with people who have a confirmed or suspected COVID-19 illness and washing hands  or using alcohol-based hand sanitizer.

Research suggests that people who get a COVID-19 infection after vaccination are less likely to report Long COVID, compared to people who are unvaccinated.

CDC, other federal agencies, and non-federal partners are working to identify further measures to lessen a person’s risk of developing Long COVID. Learn more about protecting yourself and others from COVID-19 .

Living with Long COVID

Living with Long COVID can be hard, especially when there are no immediate answers or solutions.

People experiencing Long COVID can seek care from a healthcare provider to come up with a personal medical management plan that can help improve their symptoms and quality of life. Review these tips  to help prepare for a healthcare provider appointment for Long COVID. In addition, there are many support groups being organized that can help patients and their caregivers.

Although Long COVID appears to be less common in children and adolescents than in adults, long-term effects after COVID-19 do occur in children and adolescents .

Talk to your doctor if you think you or your child has Long COVID. Learn more: Tips for Talking to Your Healthcare Provider about Post-COVID Conditions

Data for Long COVID

Studies are in progress to better understand Long COVID and how many people experience them.

CDC is using multiple approaches to estimate how many people experience Long COVID. Each approach can provide a piece of the puzzle to give us a better picture of who is experiencing Long COVID. For example, some studies look for the presence of Long COVID based on self-reported symptoms, while others collect symptoms and conditions recorded in medical records. Some studies focus only on people who have been hospitalized, while others include people who were not hospitalized. The estimates for how many people experience Long COVID can be quite different depending on who was included in the study, as well as how and when the study collected information.  Estimates of the proportion of people who had COVID-19 that go on to experience Long COVID can vary.

CDC posts data on Long COVID and provides analyses, the most recent of which can be found on the U.S. Census Bureau’s Household Pulse Survey .

CDC and other federal agencies, as well as academic institutions and research organizations, are working to learn more about the short- and long-term health effects associated with COVID-19 , who gets them and why.

Scientists are also learning more about how new variants could potentially affect Long COVID. We are still learning to what extent certain groups are at higher risk, and if different groups of people tend to experience different types of Long COVID. CDC has several studies that will help us better understand Long COVID and how healthcare providers can treat or support patients with these long-term effects. CDC will continue to share information with healthcare providers to help them evaluate and manage these conditions.

CDC is working to:

• Better identify the most frequent symptoms and diagnoses experienced by patients with Long COVID.
• Better understand how many people are affected by Long COVID, and how often people who are infected with COVID-19 develop Long COVID
• Better understand risk factors and protective factors, including which groups might be more at risk, and if different groups experience different symptoms.
• Help understand how Long COVID limit or restrict people’s daily activity.
• Help identify groups that have been more affected by Long COVID, lack access to care and treatment for Long COVID, or experience stigma.
• Better understand the role vaccination plays in preventing Long COVID.
• Collaborate with professional medical groups to develop and offer clinical guidance and other educational materials for healthcare providers, patients, and the public.

Related Pages

• Caring for People with Post-COVID Conditions
• Preparing for Appointments for Post-COVID Conditions
• Researching COVID to Enhance Recovery
• Guidance on “Long COVID” as a Disability Under the ADA

For Healthcare Professionals

• Post-COVID Conditions: Healthcare Providers

Search for and find historical COVID-19 pages and files. Please note the content on these pages and files is no longer being updated and may be out of date.

• Visit archive.cdc.gov for a historical snapshot of the COVID-19 website, capturing the end of the Federal Public Health Emergency on June 28, 2023.
• Visit the dynamic COVID-19 collection  to search the COVID-19 website as far back as July 30, 2021.

To receive email updates about COVID-19, enter your email address:

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• The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website.
• Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
• You will be subject to the destination website's privacy policy when you follow the link.
• CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website.

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What is cloud computing?

With cloud computing, organizations essentially buy a range of services offered by cloud service providers (CSPs). The CSP’s servers host all the client’s applications. Organizations can enhance their computing power more quickly and cheaply via the cloud than by purchasing, installing, and maintaining their own servers.

The cloud-computing model is helping organizations to scale new digital solutions with greater speed and agility—and to create value more quickly. Developers use cloud services to build and run custom applications and to maintain infrastructure and networks for companies of virtually all sizes—especially large global ones. CSPs offer services, such as analytics, to handle and manipulate vast amounts of data. Time to market accelerates, speeding innovation to deliver better products and services across the world.

What are examples of cloud computing’s uses?

Get to know and directly engage with senior mckinsey experts on cloud computing.

Brant Carson is a senior partner in McKinsey’s Vancouver office; Chandra Gnanasambandam and Anand Swaminathan are senior partners in the Bay Area office; William Forrest is a senior partner in the Chicago office; Leandro Santos is a senior partner in the Atlanta office; Kate Smaje is a senior partner in the London office.

Cloud computing came on the scene well before the global pandemic hit, in 2020, but the ensuing digital dash  helped demonstrate its power and utility. Here are some examples of how businesses and other organizations employ the cloud:

• A fast-casual restaurant chain’s online orders multiplied exponentially during the 2020 pandemic lockdowns, climbing to 400,000 a day, from 50,000. One pleasant surprise? The company’s online-ordering system could handle the volume—because it had already migrated to the cloud . Thanks to this success, the organization’s leadership decided to accelerate its five-year migration plan to less than one year.
• A biotech company harnessed cloud computing to deliver the first clinical batch of a COVID-19 vaccine candidate for Phase I trials in just 42 days—thanks in part to breakthrough innovations using scalable cloud data storage and computing  to facilitate processes ensuring the drug’s safety and efficacy.
• Banks use the cloud for several aspects of customer-service management. They automate transaction calls using voice recognition algorithms and cognitive agents (AI-based online self-service assistants directing customers to helpful information or to a human representative when necessary). In fraud and debt analytics, cloud solutions enhance the predictive power of traditional early-warning systems. To reduce churn, they encourage customer loyalty through holistic retention programs managed entirely in the cloud.
• Automakers are also along for the cloud ride . One company uses a common cloud platform that serves 124 plants, 500 warehouses, and 1,500 suppliers to consolidate real-time data from machines and systems and to track logistics and offer insights on shop floor processes. Use of the cloud could shave 30 percent off factory costs by 2025—and spark innovation at the same time.

That’s not to mention experiences we all take for granted: using apps on a smartphone, streaming shows and movies, participating in videoconferences. All of these things can happen in the cloud.

Learn more about our Cloud by McKinsey , Digital McKinsey , and Technology, Media, & Telecommunications  practices.

How has cloud computing evolved?

Going back a few years, legacy infrastructure dominated IT-hosting budgets. Enterprises planned to move a mere 45 percent of their IT-hosting expenditures to the cloud by 2021. Enter COVID-19, and 65 percent of the decision makers surveyed by McKinsey increased their cloud budgets . An additional 55 percent ended up moving more workloads than initially planned. Having witnessed the cloud’s benefits firsthand, 40 percent of companies expect to pick up the pace of implementation.

The cloud revolution has actually been going on for years—more than 20, if you think the takeoff point was the founding of Salesforce, widely seen as the first software as a service (SaaS) company. Today, the next generation of cloud, including capabilities such as serverless computing, makes it easier for software developers to tweak software functions independently, accelerating the pace of release, and to do so more efficiently. Businesses can therefore serve customers and launch products in a more agile fashion. And the cloud continues to evolve.

Introducing McKinsey Explainers : Direct answers to complex questions

Cost savings are commonly seen as the primary reason for moving to the cloud but managing those costs requires a different and more dynamic approach focused on OpEx rather than CapEx. Financial-operations (or FinOps) capabilities  can indeed enable the continuous management and optimization of cloud costs . But CSPs have developed their offerings so that the cloud’s greatest value opportunity is primarily through business innovation and optimization. In 2020, the top-three CSPs reached $100 billion  in combined revenues—a minor share of the global $2.4 trillion market for enterprise IT services—leaving huge value to be captured. To go beyond merely realizing cost savings, companies must activate three symbiotic rings of cloud value creation : strategy and management, business domain adoption, and foundational capabilities.

What’s the main reason to move to the cloud?

The pandemic demonstrated that the digital transformation can no longer be delayed—and can happen much more quickly than previously imagined. Nothing is more critical to a corporate digital transformation than becoming a cloud-first business. The benefits are faster time to market, simplified innovation and scalability, and reduced risk when effectively managed. The cloud lets companies provide customers with novel digital experiences—in days, not months—and delivers analytics absent on legacy platforms. But to transition to a cloud-first operating model, organizations must make a collective effort that starts at the top. Here are three actions CEOs can take to increase the value their companies get from cloud computing :

• Establish a sustainable funding model.
• Develop a new business technology operating model.
• Set up policies to attract and retain the right engineering talent.

How much value will the cloud create?

Fortune 500 companies adopting the cloud could realize more than $1 trillion in value  by 2030, and not from IT cost reductions alone, according to McKinsey’s analysis of 700 use cases.

For example, the cloud speeds up design, build, and ramp-up, shortening time to market when companies have strong DevOps (the combination of development and operations) processes in place; groups of software developers customize and deploy software for operations that support the business. The cloud’s global infrastructure lets companies scale products almost instantly to reach new customers, geographies, and channels. Finally, digital-first companies use the cloud to adopt emerging technologies and innovate aggressively, using digital capabilities as a competitive differentiator to launch and build businesses .

If companies pursue the cloud’s vast potential in the right ways, they will realize huge value. Companies across diverse industries have implemented the public cloud and seen promising results. The successful ones defined a value-oriented strategy across IT and the business, acquired hands-on experience operating in the cloud, adopted a technology-first approach, and developed a cloud-literate workforce.

Learn more about our Cloud by McKinsey and Digital McKinsey practices.

What is the cloud cost/procurement model?

Some cloud services, such as server space, are leased. Leasing requires much less capital up front than buying, offers greater flexibility to switch and expand the use of services, cuts the basic cost of buying hardware and software upfront, and reduces the difficulties of upkeep and ownership. Organizations pay only for the infrastructure and computing services that meet their evolving needs. But an outsourcing model  is more apt than other analogies: the computing business issues of cloud customers are addressed by third-party providers that deliver innovative computing services on demand to a wide variety of customers, adapt those services to fit specific needs, and work to constantly improve the offering.

What are cloud risks?

The cloud offers huge cost savings and potential for innovation. However, when companies migrate to the cloud, the simple lift-and-shift approach doesn’t reduce costs, so companies must remediate their existing applications to take advantage of cloud services.

For instance, a major financial-services organization  wanted to move more than 50 percent of its applications to the public cloud within five years. Its goals were to improve resiliency, time to market, and productivity. But not all its business units needed to transition at the same pace. The IT leadership therefore defined varying adoption archetypes to meet each unit’s technical, risk, and operating-model needs.

Legacy cybersecurity architectures and operating models can also pose problems when companies shift to the cloud. The resulting problems, however, involve misconfigurations rather than inherent cloud security vulnerabilities. One powerful solution? Securing cloud workloads for speed and agility : automated security architectures and processes enable workloads to be processed at a much faster tempo.

What kind of cloud talent is needed?

The talent demands of the cloud differ from those of legacy IT. While cloud computing can improve the productivity of your technology, it requires specialized and sometimes hard-to-find talent—including full-stack developers, data engineers, cloud-security engineers, identity- and access-management specialists, and cloud engineers. The cloud talent model  should thus be revisited as you move forward.

Six practical actions can help your organization build the cloud talent you need :

• Find engineering talent with broad experience and skills.
• Balance talent maturity levels and the composition of teams.
• Build an extensive and mandatory upskilling program focused on need.
• Build an engineering culture that optimizes the developer experience.
• Consider using partners to accelerate development and assign your best cloud leaders as owners.
• Retain top talent by focusing on what motivates them.

How do different industries use the cloud?

Different industries are expected to see dramatically different benefits from the cloud. High-tech, retail, and healthcare organizations occupy the top end of the value capture continuum. Electronics and semiconductors, consumer-packaged-goods, and media companies make up the middle. Materials, chemicals, and infrastructure organizations cluster at the lower end.

Nevertheless, myriad use cases provide opportunities to unlock value across industries , as the following examples show:

• a retailer enhancing omnichannel  fulfillment, using AI to optimize inventory across channels and to provide a seamless customer experience
• a healthcare organization implementing remote heath monitoring to conduct virtual trials and improve adherence
• a high-tech company using chatbots to provide premier-level support combining phone, email, and chat
• an oil and gas company employing automated forecasting to automate supply-and-demand modeling and reduce the need for manual analysis
• a financial-services organization implementing customer call optimization using real-time voice recognition algorithms to direct customers in distress to experienced representatives for retention offers
• a financial-services provider moving applications in customer-facing business domains to the public cloud to penetrate promising markets more quickly and at minimal cost
• a health insurance carrier accelerating the capture of billions of dollars in new revenues by moving systems to the cloud to interact with providers through easier onboarding

The cloud is evolving  to meet the industry-specific needs of companies. From 2021 to 2024, public-cloud spending on vertical applications (such as warehouse management in retailing and enterprise risk management in banking) is expected to grow by more than 40 percent annually. Spending on horizontal workloads (such as customer relationship management) is expected to grow by 25 percent. Healthcare and manufacturing organizations, for instance, plan to spend around twice as much on vertical applications as on horizontal ones.

Learn more about our Cloud by McKinsey , Digital McKinsey , Financial Services , Healthcare Systems & Services , Retail , and Technology, Media, & Telecommunications  practices.

What are the biggest cloud myths?

Views on cloud computing can be clouded by misconceptions. Here are seven common myths about the cloud —all of which can be debunked:

• The cloud’s value lies primarily in reducing costs.
• Cloud computing costs more than in-house computing.
• On-premises data centers are more secure than the cloud.
• Applications run more slowly in the cloud.
• The cloud eliminates the need for infrastructure.
• The best way to move to the cloud is to focus on applications or data centers.
• You must lift and shift applications as-is or totally refactor them.

How large must my organization be to benefit from the cloud?

Here’s one more huge misconception: the cloud is just for big multinational companies. In fact, cloud can help make small local companies become multinational. A company’s benefits from implementing the cloud are not constrained by its size. In fact, the cloud shifts barrier to entry skill rather than scale, making it possible for a company of any size to compete if it has people with the right skills. With cloud, highly skilled small companies can take on established competitors. To realize the cloud’s immense potential value fully, organizations must take a thoughtful approach, with IT and the businesses working together.

For more in-depth exploration of these topics, see McKinsey’s Cloud Insights collection. Learn more about Cloud by McKinsey —and check out cloud-related job opportunities if you’re interested in working at McKinsey.

Articles referenced include:

• “ Six practical actions for building the cloud talent you need ,” January 19, 2022, Brant Carson , Dorian Gärtner , Keerthi Iyengar, Anand Swaminathan , and Wayne Vest
• “ Cloud-migration opportunity: Business value grows, but missteps abound ,” October 12, 2021, Tara Balakrishnan, Chandra Gnanasambandam , Leandro Santos , and Bhargs Srivathsan
• “ Cloud’s trillion-dollar prize is up for grabs ,” February 26, 2021, Will Forrest , Mark Gu, James Kaplan , Michael Liebow, Raghav Sharma, Kate Smaje , and Steve Van Kuiken
• “ Unlocking value: Four lessons in cloud sourcing and consumption ,” November 2, 2020, Abhi Bhatnagar , Will Forrest , Naufal Khan , and Abdallah Salami
• “ Three actions CEOs can take to get value from cloud computing ,” July 21, 2020, Chhavi Arora , Tanguy Catlin , Will Forrest , James Kaplan , and Lars Vinter

Want to know more about cloud computing?

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Clinical Spectrum of SARS-CoV-2 Infection

Last Updated: February 29, 2024

Patients with SARS-CoV-2 infection can experience a range of clinical manifestations, from no symptoms to critical illness. In general, adults with SARS-CoV-2 infection can be grouped into the following severity of illness categories; however, the criteria for each category may overlap or vary across clinical guidelines and clinical trials, and a patient’s clinical status may change over time.

• Asymptomatic or presymptomatic infection: Individuals who test positive for SARS-CoV-2 using a virologic test (i.e., a nucleic acid amplification test [NAAT] or an antigen test) but have no symptoms consistent with COVID-19.
• Mild illness: Individuals who have any of the various signs and symptoms of COVID-19 (e.g., fever, cough, sore throat, malaise, headache, muscle pain, nausea, vomiting, diarrhea, loss of taste and smell) but do not have shortness of breath, dyspnea, or abnormal chest imaging.
• Moderate illness: Individuals who show evidence of lower respiratory disease during clinical assessment or imaging and who have an oxygen saturation measured by pulse oximetry (SpO 2 ) ≥94% on room air at sea level.
• Severe illness: Individuals who have an SpO 2 <94% on room air at sea level, a ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO 2 /FiO 2 ) <300 mm Hg, a respiratory rate >30 breaths/min, or lung infiltrates >50%.
• Critical illness: Individuals who have respiratory failure, septic shock, or multiple organ dysfunction.

SpO 2 is a key parameter for defining the illness categories listed above. However, pulse oximetry has important limitations (discussed in more detail below). Clinicians who use SpO 2 when assessing a patient must be aware of those limitations and conduct the assessment in the context of that patient’s clinical status.

The risk of progressing to severe disease increases with age and the number of underlying conditions. Patients aged ≥50 years, especially those aged ≥65 years, and patients who are immunosuppressed, unvaccinated, or not up to date with COVID-19 vaccinations are at a higher risk of progressing to severe COVID-19. 1,2 Certain underlying conditions are also associated with a higher risk of severe COVID-19, including cancer, cardiovascular disease, chronic kidney disease, chronic liver disease, chronic lung disease, diabetes, advanced or untreated HIV infection, obesity, pregnancy, cigarette smoking, and being a recipient of immunosuppressive therapy or a transplant. 3 Health care providers should closely monitor patients who have COVID-19 and any of these conditions until clinical recovery is achieved.

The initial evaluation for patients may include chest imaging (e.g., X-ray, ultrasound or computed tomography scan) and an electrocardiogram, if indicated. Laboratory testing should include a complete blood count with differential and a metabolic profile, including liver and renal function tests. Although inflammatory markers such as C-reactive protein (CRP), D-dimer, and ferritin are not routinely measured as part of standard care, results from such measurements may have prognostic value. 4-7

The definitions for the severity of illness categories also apply to pregnant patients. However, the threshold for certain interventions is different for pregnant and nonpregnant patients. For example, oxygen supplementation for pregnant patients is generally used when SpO 2 falls below 95% on room air at sea level to accommodate the physiologic changes in oxygen demand during pregnancy and to ensure adequate oxygen delivery to the fetus. 8  

If laboratory parameters are used for monitoring pregnant patients and making decisions about interventions, clinicians should be aware that normal physiologic changes during pregnancy can alter several laboratory values. In general, leukocyte cell count increases throughout gestation and delivery and peaks during the immediate postpartum period. This increase is mainly due to neutrophilia. 9 D-dimer and CRP levels also increase during pregnancy and are often higher in pregnant patients than in nonpregnant patients. 10 Detailed information on treating COVID-19 in pregnant patients can be found in Special Considerations During Pregnancy and After Delivery and in the pregnancy considerations subsections in the Guidelines. 

In children with COVID-19, radiographic abnormalities are common and, for the most part, should not be the only criteria used to determine the severity of illness. The normal values for respiratory rate also vary with age in children. Therefore, hypoxemia should be the primary criterion used to define severe COVID-19, especially in younger children. In a small subset of children and young adults, SARS-CoV-2 infection may be followed by the severe inflammatory condition multisystem inflammatory syndrome in children (MIS-C). 11,12 This syndrome is discussed in detail in Special Considerations in Children .

Clinical Considerations for the Use of Pulse Oximetry

During the COVID-19 pandemic, the use of pulse oximetry to assess and monitor patients’ oxygenation status increased in hospital, outpatient health care facility, and home settings. Although pulse oximetry is useful for estimating blood oxygen levels, pulse oximeters may not accurately detect hypoxemia under certain circumstances. To avoid delays in recognizing hypoxemia, clinicians who use pulse oximetry to assist with clinical decisions should keep these limitations in mind.

Pulse oximetry results can be affected by skin pigmentation, thickness, or temperature. Poor blood circulation or the use of tobacco or fingernail polish also may affect results. The Food and Drug Administration (FDA) advises clinicians to refer to the label or manufacturer website of a pulse oximeter or sensor to ascertain its accuracy. 13 The FDA also advises using pulse oximetry only as an estimate of blood oxygen saturation, because an SpO 2 reading represents a range of arterial oxygen saturation (SaO 2 ). For example, an SpO 2 reading of 90% may represent a range of SaO 2 from 86% to 94%. Studies that compared SpO 2 and SaO 2 levels measured before the pandemic found that pulse oximeters overestimated oxygen saturation in people who were classified as having darker skin pigmentation and in people whose race or ethnic origin was reported as non-Hispanic Black, Black, or African American. 14,15

Several published reports have compared SpO 2 and SaO 2 measurements in patients with COVID-19, including children. 14,16-18 The studies demonstrated that occult hypoxemia (defined as an SaO 2 <88% despite an SpO 2 >92%) was more common in patients with darker skin pigmentation, which may result in adverse consequences. The likelihood of error was greater in the lower ranges of SpO 2 . In 1 of these studies, occult hypoxemia was associated with more organ dysfunction and hospital mortality. 17 These studies did not specify the specific devices used to assess SpO 2 levels. The FDA has recognized the need for better real-world evidence to address ongoing concerns about the accuracy of pulse oximeters when they are used to measure oxygen saturation in people with darker skin pigmentation. 19

A 5-hospital registry study of patients evaluated in the emergency department or hospitalized for COVID-19 found that 24% were not identified as eligible for treatment due to overestimation of SaO 2 . 20 The majority of patients (55%) who were not identified as eligible were Black. The study also examined the amount of time delay patients experienced before being identified as eligible for treatment. The median delay for patients who were Black was 1 hour longer than the delay for patients who were White. 

In pulse oximetry, skin tone is an important variable, but accurately measuring oxygen saturation is a complex process. One observational study in adults was unable to identify a consistently predictable difference between SaO 2 and SpO 2 over time for individual patients. 16 Factors other than skin pigmentation (e.g., peripheral perfusion, pulse oximeter sensor placement) are likely involved.

Despite the limitations of pulse oximetry, an FDA-cleared pulse oximeter for home use can contribute to an assessment of a patient’s overall clinical status. Practitioners should advise patients to follow the manufacturer’s instructions for use, place the oximeter on the index or ring finger, and ensure the hand is warm, relaxed, and held below the level of the heart. Fingernail polish should be removed before testing. Patients should be at rest, indoors, and breathing quietly without talking for several minutes before testing. Rather than accepting the first reading, patients or caretakers should observe the readings on the pulse oximeter for ≥30 seconds until a steady number is displayed and inform their health care provider if the reading is repeatedly below a previously specified value (generally 95% on room air at sea level). 13,21 Pulse oximetry has been widely adopted as a remote patient monitoring tool, but when the use of pulse oximeters is compared with close monitoring of clinical progress via video consultation, telephone calls, text messaging, or home visits, there is insufficient evidence that it improves clinical outcomes. 22,23

Not all commercially available pulse oximeters have been cleared by the FDA. SpO 2 readings obtained through devices not cleared by the FDA, such as over-the-counter sports oximeters or mobile phone applications, lack sufficient accuracy for clinical use. Abnormal readings on these devices should be confirmed with an FDA-cleared device or an arterial blood gas analysis. 24,25

Regardless of the setting, SpO 2 should always be interpreted within the context of a patient’s entire clinical presentation. Regardless of a pulse oximeter reading, a patient’s signs and symptoms (e.g., dyspnea, tachypnea, chest pain, changes in cognition or attentional state, cyanosis) should be evaluated. 

Asymptomatic or Presymptomatic Infection

Asymptomatic SARS-CoV-2 infection can occur, although the percentage of patients who remain truly asymptomatic throughout the course of infection is variable and incompletely defined. The percentage of individuals who present with asymptomatic infection and progress to clinical disease is unclear. Some asymptomatic individuals have been reported to have objective radiographic findings consistent with COVID-19 pneumonia. 26,27  

Mild Illness

Patients with mild illness may exhibit a variety of signs and symptoms (e.g., fever, cough, sore throat, malaise, headache, muscle pain, nausea, vomiting, diarrhea, loss of taste and smell). They do not have shortness of breath, dyspnea on exertion, or abnormal imaging. Most patients who are mildly ill can be managed in an ambulatory setting or at home. No imaging or specific laboratory evaluations are routinely indicated in otherwise healthy patients with mild COVID-19. Patients aged ≥50 years, especially those aged ≥65 years, patients with certain underlying comorbidities, and patients who are immunosuppressed, unvaccinated, or not up to date with COVID-19 vaccinations are at higher risk of disease progression and are candidates for antiviral therapy. 1,2 See Therapeutic Management of Nonhospitalized Adults With COVID-19 for recommendations regarding anti-SARS-CoV-2 therapies. 

Moderate Illness

Moderate illness is defined as evidence of lower respiratory disease during clinical assessment or imaging, with an SpO 2 ≥94% on room air at sea level. Given that pulmonary disease can progress rapidly in patients with COVID-19, patients with moderate disease should be closely monitored. See Therapeutic Management of Nonhospitalized Adults With COVID-19 for recommendations regarding anti-SARS-CoV-2 therapies in patients at high risk of progression to severe disease. 

Severe Illness 

Patients with COVID-19 are considered to have severe illness if they have an SpO 2 <94% on room air at sea level, PaO 2 /FiO 2 <300 mm Hg, a respiratory rate >30 breaths/min, or lung infiltrates >50%. These patients may experience rapid clinical deterioration and should be given oxygen therapy and hospitalized. See Therapeutic Management of Hospitalized Adults With COVID-19 for treatment recommendations. 

Critical Illness 

SARS-CoV-2 infection can cause acute respiratory distress syndrome, virus-induced distributive (septic) shock, cardiac shock, an exaggerated inflammatory response, thrombotic disease, and exacerbation of underlying comorbidities.

The clinical management of patients with COVID-19 who are in the intensive care unit should include treatment with immunomodulators and, in some cases, the addition of remdesivir. These patients should also receive treatment for any comorbid conditions and nosocomial complications. For more information, see Critical Care for Adults and Therapeutic Management of Hospitalized Adults With COVID-19 .

Infectious Complications in Patients With COVID-19

Some patients with COVID-19 may have additional infections when they present for care or that develop during the course of treatment. These coinfections may complicate treatment and recovery. Older patients or those with certain comorbidities or immunocompromising conditions may be at higher risk for these infections. The use of immunomodulators such as dexamethasone, Janus kinase inhibitors (e.g., baricitinib, tofacitinib), interleukin-6 inhibitors (e.g., tocilizumab, sarilumab), tumor necrosis factor inhibitors (e.g., infliximab), or abatacept to treat COVID-19 may also increase the risk of infectious complications. However, when these therapies are used appropriately, the benefits outweigh the risks. 

Infectious complications in patients with COVID-19 can be categorized as follows:

• Coinfections at presentation: Although most individuals present with only SARS-CoV-2 infection, concomitant viral infections, including influenza and other respiratory viruses, have been reported. 28-30 Community-acquired bacterial pneumonia has also been reported, but it is uncommon. 28,31,32 Antibacterial therapy is generally not recommended unless additional evidence for bacterial pneumonia is present (e.g., leukocytosis, the presence of a focal infiltrate on imaging).
• Reactivation of latent infections: There are case reports of underlying chronic hepatitis B virus and latent tuberculosis infections reactivating in patients with COVID-19 who receive immunomodulators as treatment, although the data are currently limited. 33-35 Reactivation of herpes simplex virus and varicella zoster virus infections have also been reported. 36 Cases of severe and disseminated strongyloidiasis have been reported in patients with COVID-19 during treatment with tocilizumab and corticosteroids. 37,38 Many clinicians would initiate empiric treatment (e.g., with the antiparasitic drug ivermectin), with or without serologic testing, in patients who require immunomodulators for the treatment of COVID-19 and have come from areas where Strongyloides is endemic (i.e., tropical, subtropical, or warm temperate areas). 39,40
• Nosocomial infections: Hospitalized patients with COVID-19 may acquire common nosocomial infections, such as hospital-acquired pneumonia (including ventilator-associated pneumonia), line-related bacteremia or fungemia, catheter-associated urinary tract infection, and diarrhea associated with Clostridioides difficile . 41,42 Early diagnosis and treatment of these infections are important for improving outcomes in these patients.
• Opportunistic fungal infections: Invasive fungal infections, including aspergillosis and mucormycosis, have been reported in hospitalized patients with COVID-19. 43-46 Although these infections are relatively rare, they can be fatal, and they may be seen more commonly in patients who are immunocompromised or receiving mechanical ventilation. The majority of mucormycosis cases have been reported in India and are associated with diabetes mellitus or the use of corticosteroids. 47,48 The approach for managing these fungal infections should be the same as the approach for managing invasive fungal infections in other settings. 

SARS-CoV-2 Reinfection and Breakthrough Infection

As seen with other respiratory viral infections, reinfection after recovery from prior infection has been reported for SARS-CoV-2. 49 Reinfection may occur as initial immune responses to the primary infection wane over time. Data regarding the prevalence, risk factors, timing, and severity of reinfection are evolving and vary depending on the circulating variants. Breakthrough SARS-CoV-2 infections (i.e., infection in people who are up to date with COVID-19 vaccinations) also occur. 50 When compared with infection in people who are unvaccinated, breakthrough infections in vaccinated individuals appear less likely to lead to severe illness or symptoms that persist ≥28 days. 50-53 The time to breakthrough infection has been reported to be shorter for patients with immunocompromising conditions (i.e., solid organ or bone marrow transplant recipients or people with HIV) than for those with no immunocompromising conditions. 50

Although data are limited, no evidence suggests that the treatment of suspected or documented SARS-CoV-2 reinfection or breakthrough infection should be different from the treatment used during the initial infection, as outlined in Therapeutic Management of Nonhospitalized Adults With COVID-19 and Therapeutic Management of Hospitalized Adults With COVID-19 . 

Prolonged Viral Shedding, Persistent Symptoms, and Other Conditions After SARS-CoV-2 Infection

Symptomatic SARS-CoV-2 infection is typically associated with a decline in viral shedding and resolution of COVID-19 symptoms over days to weeks. However, in some cases, reduced viral shedding and symptom resolution are followed by viral or symptom rebound. People who are immunocompromised may experience viral shedding for many weeks. Some people experience symptoms that develop or persist for more than 4 weeks after the initial COVID-19 diagnosis. 

Viral or Symptom Rebound Soon After COVID-19

Observational studies and results from clinical trials of therapeutic agents have described SARS-CoV-2 viral or COVID-19 symptom rebound in patients who have completed treatment for COVID-19. 54-56 Viral and symptom rebounds have also occurred when anti-SARS-CoV-2 therapies were not used. 56,57 Typically, this phenomenon has not been associated with progression to severe COVID-19.

Prolonged Viral Shedding in Patients Who Are Immunocompromised

Patients who are immunocompromised may experience prolonged shedding of SARS-CoV-2 with or without COVID-19 symptoms. 58,59 Prolonged viral shedding may affect SARS-CoV-2 testing strategies and isolation duration for these patients. In some cases, the prolonged shedding may be associated with persistent COVID-19 symptoms. See Special Considerations in People Who Are Immunocompromised for more information on the clinical management of people who are immunocompromised. 

Persistent, New, or Recurrent Symptoms More Than 4 Weeks After SARS-CoV-2 Infection 

Some patients report persistent, new, or recurrent symptoms and conditions (e.g., cardiopulmonary injury, neurocognitive impairment, new-onset diabetes, gastrointestinal and dermatologic manifestations) more than 4 weeks after the initial COVID-19 diagnosis. 60 The nomenclature for this phenomenon is evolving; no clinical terminology has been established. The terminology used includes long COVID, post-COVID condition, post–COVID-19 syndrome, and post-acute sequelae of SARS-CoV-2. Patients who have these symptoms or conditions have been called “long haulers.” 

Data on the incidence, natural history, and etiology of these symptoms are emerging. However, reports on these syndromes have several limitations, such as differing case definitions, a lack of comparator groups, and overlap between the reported symptoms and the symptoms of post-intensive care syndrome that have been described in patients without COVID-19. In addition, many reports only included patients who attended post-COVID clinics. Details on the pathogenesis, clinical presentation, and treatment for these conditions are beyond the scope of these Guidelines. The Centers for Disease Control and Prevention provides information about the timeframes, presentation of symptoms, and management strategies for post-COVID conditions. Research on the prevalence, characteristics, and pathophysiology of persistent symptoms and conditions after COVID-19 is ongoing, including research through the National Institutes of Health’s RECOVER Initiative , which aims to inform potential therapeutic strategies.

MIS-C and multisystem inflammatory syndrome in adults (MIS-A) are serious postinfectious complications of SARS-CoV-2 infection. For more information on these syndromes, see Therapeutic Management of Hospitalized Children With MIS-C, Plus a Discussion on MIS-A .

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• Aldhaleei WA, Alnuaimi A, Bhagavathula AS. COVID-19 induced hepatitis B virus reactivation: a novel case from the United Arab Emirates. Cureus . 2020;12(6):e8645. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32550096 .
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• Marchese V, Crosato V, Gulletta M, et al. Strongyloides infection manifested during immunosuppressive therapy for SARS-CoV-2 pneumonia. Infection . 2021;49(3):539-542. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32910321 .
• Stauffer WM, Alpern JD, Walker PF. COVID-19 and dexamethasone: a potential strategy to avoid steroid-related Strongyloides hyperinfection. JAMA. 2020;324(7):623-624. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32761166 .
• Mohareb AM, Rosenberg JM, Bhattacharyya RP, et al. Preventing infectious complications of immunomodulation in COVID-19 in foreign-born patients. J Immigr Minor Health . 2021;23(6):1343-1347. Available at: https://www.ncbi.nlm.nih.gov/pubmed/34159495 .
• Bardi T, Pintado V, Gomez-Rojo M, et al. Nosocomial infections associated to COVID-19 in the intensive care unit: clinical characteristics and outcome. Eur J Clin Microbiol Infect Dis . 2021;40(3):495-502. Available at: https://www.ncbi.nlm.nih.gov/pubmed/33389263 .
• Lingscheid T, Lippert LJ, Hillus D, et al. Characterization of antimicrobial use and co-infections among hospitalized patients with COVID-19: a prospective observational cohort study. Infection . 2022;50(6):1441-1452. Available at: https://www.ncbi.nlm.nih.gov/pubmed/35420370 .
• Salmanton-García J, Sprute R, Stemler J, et al. COVID-19-associated pulmonary aspergillosis, March–August 2020. Emerg Infect Dis . 2021;27(4):1077-1086. Available at: https://www.ncbi.nlm.nih.gov/pubmed/33539721 .
• Chong WH, Neu KP. Incidence, diagnosis and outcomes of COVID-19-associated pulmonary aspergillosis (CAPA): a systematic review. J Hosp Infect . 2021;113:115-129. Available at: https://www.ncbi.nlm.nih.gov/pubmed/33891985 .
• Machado M, Valerio M, Álvarez-Uría A, et al. Invasive pulmonary aspergillosis in the COVID-19 era: an expected new entity. Mycoses . 2021;64(2):132-143. Available at: https://www.ncbi.nlm.nih.gov/pubmed/33210776 .
• Yusuf E, Seghers L, Hoek RAS, et al. Aspergillus in critically ill COVID-19 patients: a scoping review. J Clin Med . 2021;10(11):2469. Available at: https://www.ncbi.nlm.nih.gov/pubmed/34199528 .
• Singh AK, Singh R, Joshi SR, Misra A. Mucormycosis in COVID-19: a systematic review of cases reported worldwide and in India. Diabetes Metab Syndr . 2021;15(4):102146. Available at: https://www.ncbi.nlm.nih.gov/pubmed/34192610 .
• Pal R, Singh B, Bhadada SK, et al. COVID-19-associated mucormycosis: an updated systematic review of literature. Mycoses . 2021;64(12):1452-1459. Available at: https://www.ncbi.nlm.nih.gov/pubmed/34133798 .
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• Link-Gelles R, Ciesla AA, Roper LE, et al. Early estimates of bivalent mRNA booster dose vaccine effectiveness in preventing symptomatic SARS-CoV-2 infection attributable to Omicron BA.5- and XBB/XBB.1.5-related sublineages among immunocompetent adults—increasing community access to testing program, United States, December 2022–January 2023. MMWR Morb Mortal Wkly Rep . 2023;72(5):119-124. Available at: https://pubmed.ncbi.nlm.nih.gov/36730051 .
• Antonelli M, Penfold RS, Merino J, et al. Risk factors and disease profile of post-vaccination SARS-CoV-2 infection in UK users of the COVID Symptom Study app: a prospective, community-based, nested, case-control study. Lancet Infect Dis . 2022;22(1):43-55. Available at: https://www.ncbi.nlm.nih.gov/pubmed/34480857 .
• Kuodi P, Gorelik Y, Zayyad H, et al. Association between BNT162b2 vaccination and reported incidence of post-COVID-19 symptoms: cross-sectional study 2020–21, Israel. NPJ Vaccines . 2022;7(1):101. Available at: https://pubmed.ncbi.nlm.nih.gov/36028498 .
• Charness ME, Gupta K, Stack G, et al. Rebound of SARS-CoV-2 infection after nirmatrelvir-ritonavir treatment. N Engl J Med . 2022;387(11):1045-1047. Available at: https://www.ncbi.nlm.nih.gov/pubmed/36069968 .
• Boucau J, Uddin R, Marino C, et al. Characterization of virologic rebound following nirmatrelvir-ritonavir treatment for coronavirus disease 2019 (COVID-19). Clin Infect Dis . 2023;76(3):e526-e529. Available at: https://www.ncbi.nlm.nih.gov/pubmed/35737946 .
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• Qutub M, Aldabbagh Y, Mehdawi F, et al. Duration of viable SARS-CoV-2 shedding from respiratory tract in different human hosts and its impact on isolation discontinuation polices revision; a narrative review. Clin Infect Pract . 2022;13:100140. Available at: https://www.ncbi.nlm.nih.gov/pubmed/35190799 .
• Tarhini H, Recoing A, Bridier-Nahmias A, et al. Long-term severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infectiousness among three immunocompromised patients: from prolonged viral shedding to SARS-CoV-2 superinfection. J Infect Dis . 2021;223(9):1522-1527. Available at: https://www.ncbi.nlm.nih.gov/pubmed/33556961 .
• Centers for Disease Control and Prevention. Post-COVID conditions: information for healthcare providers. 2023. Available at: https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-care/post-covid-conditions.html . Accessed January 2, 2024.

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Gadolinium-based contrast agents for MRI: safety in pregnancy

By carefully assembling and analyzing real-world evidence, FDA/CDER assessed potential serious risks of using gadolinium-based contrast agents for MRI during pregnancy.

Although clinical trials provide crucial evidence that a drug is safe and effective, drug toxicities sometimes become evident only after marketed use, when rare but serious adverse effects may be reported. To help ensure drugs are safe for patients, FDA continually monitors approved drugs under real-world conditions, and the Agency may update drug labeling or even withdraw a product from the market based on new findings. Much of the evidence pertaining to real-world experience with a drug comes from spontaneous reports to FDA’s Adverse Event Reporting System (FAERS), but CDER may also proactively address safety concerns by analyzing the data in patient medical records and information collected in the course of routine health care.

Safety concerns for gadolinium-based contrast agents

Gadolinium-based contrast agents (GBCAs) are intravenous (or IV) drugs that are given to an estimated 30-45% of patients undergoing magnetic resonance imaging (MRI) to provide detailed images. Because of its toxicity, gadolinium is complexed with a molecule called a chelator (figure 1) when used as a contrast agent. The chelator reduces toxicity by minimizing unbound gadolinium, which makes gadolinium less likely to interact with tissues in the body before the kidneys eliminate the contrast agent. However, chelators do not completely prevent patient exposure to gadolinium. Gadolinium complexed with other molecules can be found in very small amounts in various organs and tissues of patients who receive GBCAs. No long-term clinical consequences of gadolinium exposure in healthy individuals have been identified. As a precaution, FDA required medication guides for GBCAs. These guides outline what is known about the toxicities of these products and indicate that “people who get many doses of gadolinium medicines, women who are pregnant and young children may be at increased risk from gadolinium staying in the body.”

From clinical studies and initial marketing experience, adverse reactions attributed to GBCAs were described as short-term events and often categorized as allergic. However, in 2006, nephrogenic systemic fibrosis (NSF), a potentially fatal disease that occurs mainly in patients with chronic kidney disease or acute kidney failure who had undergone GBCA-MRI, was described. Currently, researchers believe that retention of gadolinium due to impaired renal function or other precipitating risk factors such as inflammation can lead to NSF, which is characterized by thickening and hardening (fibrosis) of the skin, subcutaneous tissues, and sometimes underlying skeletal muscle. There may also be serious damage to other organs, including the lungs and the heart. Boxed warnings were added to product labeling to restrict GBCA use in patients with severe renal impairment, and the number of reported NSF cases reported annually has decreased.

The scientific challenge

In 2016, a study based on health care data in Ontario, Canada, reported that GBCA-MRI exposure during pregnancy was associated with greater risk for fetal or neonatal death and rheumatological, inflammatory or infiltrative skin conditions [1]. Subsequently, an FDA-led study identified one gadolinium-exposure in-utero for every 860 pregnancies (0.12% of all pregnancies) [2]. The majority of exposures were during the first few weeks of pregnancy, a time when individuals may not know they are pregnant. FDA-approved labeling for all GBCAs was updated to state that GBCA administration should be considered during pregnancy only if imaging was essential and should not be delayed. However, for pregnant women and the clinicians who treated them, serious uncertainties remained when deciding whether a GBCA-MRI was appropriate. Limitations of the Canadian study of GBCAs in pregnant women included insufficient sample size to support a statistical comparison of contrast MRI vs non-contrast MRI, and inadequate control for the reason MRI was administered (due to missing information).

To address this research question, FDA/CDER conducted a study in collaboration with researchers at the University of Florida using data from Medicaid insurance claims and linked medical records for more than 11 million pregnancies [3]. Pregnant women whose medical history indicated that their fetuses might be at greater risk for adverse effects (for example, those whose MRI was for pelvic examination) were excluded. The final cohort of patients consisted of 782 women who had received a GBCA-MRI while pregnant and 5,209 who were exposed to MRI without GBCA while pregnant. The primary endpoint was fetal death or infant death shortly after birth (information for the latter outcome was obtained from the National Death Index or Medicaid records). A secondary endpoint was admission to the neonatal intensive care unit within seven days of birth. The investigators used a statistical technique called propensity score matching to adjust for potential confounding patient variables, such as comorbidities, pregnancy characteristics, ultrasound history, and prenatal vitamin use.

Study results and practice implications

After adjustment for potential confounding variables, the study did not identify a difference in the risk of fetal or neonatal death associated with exposure to GBCA-MRI. The risk for the patients who received a GBCA appeared similar to those who received MRI without contrast (RR = 0.73, Table 1). Similar results were obtained for the secondary outcome measured in the study, i.e., GBCAs did not appear to increase the risk that newborns who had been exposed to GBCAs were admitted to a neonatal intensive care unit.

Adjusted risks of fetal or neonatal death or NICU admission with GBCA

Reassuringly, the risk estimates did not change substantially in sensitivity analyses. The study authors concluded that gadolinium use during pregnancy should be limited and used in accordance with professional society guidelines. They also pointed out that, because there is gadolinium retention in various tissues, the impact of exposure on subacute and chronic adverse outcomes in infants remains unknown and needs further study.

This study also highlights the critical importance of the medical data that are collected during patient care for monitoring the safety of medical products. CDER is working with interested parties to make sure that these data become more standardized, interoperable, transparent and are easily linked to other kinds of data in support of studies like the one described here.

How does this research advance the safe and effective use of drugs? This RWE study of medical data from over 11 million women enrolled in Medicaid can provide valuable information to clinicians and their patients as they weigh the risks and benefits of gadolinium MRI procedures for imaging during pregnancy.

1 In this study, adjusted and unadjusted results were also highly similar for the planned outcomes. 2 In sensitivity analyses, researchers assess how sensitive the results are to changes in how the analysis is conducted and its underlying assumptions and design. For example, in this study the investigators compared the number of admissions to a neonatal ICU within seven days after birth. One sensitivity analysis consisted of using a window of 30 days to measure ICU admissions and the results were similar to those obtained in the main analysis.

[1] Ray JG, Vermeulen MJ, Bharatha A, Montanera WJ, Park AL. Association between MRI exposure during pregnancy and fetal and childhood outcomes. JAMA 2016;316(9):952-61. [2] Bird ST, Gelperin K, Sahin L, Bleich KB, Fazio-Eynullayeva E, Woods C, Radden E, Greene P, McCloskey C, Johnson T, Shinde, M. First-trimester exposure to gadolinium-based contrast agents: a utilization study of 4.6 million US pregnancies. Radiology, 2019;293(1):193-200. [3] Winterstein AG, Thai TN, Nduaguba S, Smolinski NE, Wang X, Sahin L, Krefting I, Gelperin K, Bird ST, Rasmussen SA. Risk of fetal or neonatal death or neonatal intensive care unit admission associated with gadolinium magnetic resonance imaging exposure during pregnancy. Am J Obstet Gynecol 2023;228(4):465-e1-11.

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What the data says about gun deaths in the U.S.

More Americans died of gun-related injuries in 2021 than in any other year on record, according to the latest available statistics from the Centers for Disease Control and Prevention (CDC). That included record numbers of both gun murders and gun suicides. Despite the increase in such fatalities, the rate of gun deaths – a statistic that accounts for the nation’s growing population – remained below the levels of earlier decades.

Here’s a closer look at gun deaths in the United States, based on a Pew Research Center analysis of data from the CDC, the FBI and other sources. You can also read key public opinion findings about U.S. gun violence and gun policy .

This Pew Research Center analysis examines the changing number and rate of gun deaths in the United States. It is based primarily on data from the Centers for Disease Control and Prevention (CDC) and the Federal Bureau of Investigation (FBI). The CDC’s statistics are based on information contained in official death certificates, while the FBI’s figures are based on information voluntarily submitted by thousands of police departments around the country.

For the number and rate of gun deaths over time, we relied on mortality statistics in the CDC’s WONDER database covering four distinct time periods:  1968 to 1978 ,  1979 to 1998 ,  1999 to 2020 , and 2021 . While these statistics are mostly comparable for the full 1968-2021 period, gun murders and suicides between 1968 and 1978 are classified by the CDC as involving firearms  and  explosives; those between 1979 and 2021 are classified as involving firearms only. Similarly, gun deaths involving law enforcement between 1968 and 1978 exclude those caused by “operations of war”; those between 1979 and 2021 include that category, which refers to gun deaths among military personnel or civilians  due to war or civil insurrection in the U.S . All CDC gun death estimates in this analysis are adjusted to account for age differences over time and across states.

The FBI’s statistics about the types of firearms used in gun murders in 2020 come from the bureau’s  Crime Data Explorer website . Specifically, they are drawn from the expanded homicide tables of the agency’s  2020 Crime in the United States report . The FBI’s statistics include murders and non-negligent manslaughters involving firearms.

How many people die from gun-related injuries in the U.S. each year?

In 2021, the most recent year for which complete data is available, 48,830 people died from gun-related injuries in the U.S., according to the CDC. That figure includes gun murders and gun suicides, along with three less common types of gun-related deaths tracked by the CDC: those that were accidental, those that involved law enforcement and those whose circumstances could not be determined. The total excludes deaths in which gunshot injuries played a contributing, but not principal, role. (CDC fatality statistics are based on information contained in official death certificates, which identify a single cause of death.)

What share of U.S. gun deaths are murders and what share are suicides?

Though they tend to get less public attention than gun-related murders, suicides have long accounted for the majority of U.S. gun deaths . In 2021, 54% of all gun-related deaths in the U.S. were suicides (26,328), while 43% were murders (20,958), according to the CDC. The remaining gun deaths that year were accidental (549), involved law enforcement (537) or had undetermined circumstances (458).

What share of all murders and suicides in the U.S. involve a gun?

About eight-in-ten U.S. murders in 2021 – 20,958 out of 26,031, or 81% – involved a firearm. That marked the highest percentage since at least 1968, the earliest year for which the CDC has online records. More than half of all suicides in 2021 – 26,328 out of 48,183, or 55% – also involved a gun, the highest percentage since 2001.

How has the number of U.S. gun deaths changed over time?

The record 48,830 total gun deaths in 2021 reflect a 23% increase since 2019, before the onset of the coronavirus pandemic .

Gun murders, in particular, have climbed sharply during the pandemic, increasing 45% between 2019 and 2021, while the number of gun suicides rose 10% during that span.

The overall increase in U.S. gun deaths since the beginning of the pandemic includes an especially stark rise in such fatalities among children and teens under the age of 18. Gun deaths among children and teens rose 50% in just two years , from 1,732 in 2019 to 2,590 in 2021.

How has the rate of U.S. gun deaths changed over time?

While 2021 saw the highest total number of gun deaths in the U.S., this statistic does not take into account the nation’s growing population. On a per capita basis, there were 14.6 gun deaths per 100,000 people in 2021 – the highest rate since the early 1990s, but still well below the peak of 16.3 gun deaths per 100,000 people in 1974.

The gun murder rate in the U.S. remains below its peak level despite rising sharply during the pandemic. There were 6.7 gun murders per 100,000 people in 2021, below the 7.2 recorded in 1974.

The gun suicide rate, on the other hand, is now on par with its historical peak. There were 7.5 gun suicides per 100,000 people in 2021, statistically similar to the 7.7 measured in 1977. (One caveat when considering the 1970s figures: In the CDC’s database, gun murders and gun suicides between 1968 and 1978 are classified as those caused by firearms and explosives. In subsequent years, they are classified as deaths involving firearms only.)

Which states have the highest and lowest gun death rates in the U.S.?

The rate of gun fatalities varies widely from state to state. In 2021, the states with the highest total rates of gun-related deaths – counting murders, suicides and all other categories tracked by the CDC – included Mississippi (33.9 per 100,000 people), Louisiana (29.1), New Mexico (27.8), Alabama (26.4) and Wyoming (26.1). The states with the lowest total rates included Massachusetts (3.4), Hawaii (4.8), New Jersey (5.2), New York (5.4) and Rhode Island (5.6).

The results are somewhat different when looking at gun murder and gun suicide rates separately. The places with the highest gun murder rates in 2021 included the District of Columbia (22.3 per 100,000 people), Mississippi (21.2), Louisiana (18.4), Alabama (13.9) and New Mexico (11.7). Those with the lowest gun murder rates included Massachusetts (1.5), Idaho (1.5), Hawaii (1.6), Utah (2.1) and Iowa (2.2). Rate estimates are not available for Maine, New Hampshire, Vermont or Wyoming.

The states with the highest gun suicide rates in 2021 included Wyoming (22.8 per 100,000 people), Montana (21.1), Alaska (19.9), New Mexico (13.9) and Oklahoma (13.7). The states with the lowest gun suicide rates were Massachusetts (1.7), New Jersey (1.9), New York (2.0), Hawaii (2.8) and Connecticut (2.9). Rate estimates are not available for the District of Columbia.

How does the gun death rate in the U.S. compare with other countries?

The gun death rate in the U.S. is much higher than in most other nations, particularly developed nations. But it is still far below the rates in several Latin American countries, according to a 2018 study of 195 countries and territories by researchers at the Institute for Health Metrics and Evaluation at the University of Washington.

The U.S. gun death rate was 10.6 per 100,000 people in 2016, the most recent year in the study, which used a somewhat different methodology from the CDC. That was far higher than in countries such as Canada (2.1 per 100,000) and Australia (1.0), as well as European nations such as France (2.7), Germany (0.9) and Spain (0.6). But the rate in the U.S. was much lower than in El Salvador (39.2 per 100,000 people), Venezuela (38.7), Guatemala (32.3), Colombia (25.9) and Honduras (22.5), the study found. Overall, the U.S. ranked 20th in its gun fatality rate that year .

How many people are killed in mass shootings in the U.S. every year?

This is a difficult question to answer because there is no single, agreed-upon definition of the term “mass shooting.” Definitions can vary depending on factors including the number of victims and the circumstances of the shooting.

The FBI collects data on “active shooter incidents,” which it defines as “one or more individuals actively engaged in killing or attempting to kill people in a populated area.” Using the FBI’s definition, 103 people – excluding the shooters – died in such incidents in 2021 .

The Gun Violence Archive, an online database of gun violence incidents in the U.S., defines mass shootings as incidents in which four or more people are shot, even if no one was killed (again excluding the shooters). Using this definition, 706 people died in these incidents in 2021 .

Regardless of the definition being used, fatalities in mass shooting incidents in the U.S. account for a small fraction of all gun murders that occur nationwide each year.

How has the number of mass shootings in the U.S. changed over time?

The same definitional issue that makes it challenging to calculate mass shooting fatalities comes into play when trying to determine the frequency of U.S. mass shootings over time. The unpredictability of these incidents also complicates matters: As Rand Corp. noted in a research brief , “Chance variability in the annual number of mass shooting incidents makes it challenging to discern a clear trend, and trend estimates will be sensitive to outliers and to the time frame chosen for analysis.”

The FBI found an increase in active shooter incidents between 2000 and 2021. There were three such incidents in 2000. By 2021, that figure had increased to 61.

Which types of firearms are most commonly used in gun murders in the U.S.?

In 2020, the most recent year for which the FBI has published data, handguns were involved in 59% of the 13,620 U.S. gun murders and non-negligent manslaughters for which data is available. Rifles – the category that includes guns sometimes referred to as “assault weapons” – were involved in 3% of firearm murders. Shotguns were involved in 1%. The remainder of gun homicides and non-negligent manslaughters (36%) involved other kinds of firearms or those classified as “type not stated.”

It’s important to note that the FBI’s statistics do not capture the details on all gun murders in the U.S. each year. The FBI’s data is based on information voluntarily submitted by police departments around the country, and not all agencies participate or provide complete information each year.

Note: This is an update of a post originally published on Aug. 16, 2019.

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Tinnitus can be caused by a number of things, including broken or damaged hair cells in the part of the ear that receives sound (cochlea); changes in how blood moves through nearby blood vessels (carotid artery); problems with the joint of the jaw bone (temporomandibular joint); and problems with how the brain processes sound.

Tinnitus is when you experience ringing or other noises in one or both of your ears. The noise you hear when you have tinnitus isn't caused by an external sound, and other people usually can't hear it. Tinnitus is a common problem. It affects about 15% to 20% of people, and is especially common in older adults.

Tinnitus is usually caused by an underlying condition, such as age-related hearing loss, an ear injury or a problem with the circulatory system. For many people, tinnitus improves with treatment of the underlying cause or with other treatments that reduce or mask the noise, making tinnitus less noticeable.

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Tinnitus is most often described as a ringing in the ears, even though no external sound is present. However, tinnitus can also cause other types of phantom noises in your ears, including:

Most people who have tinnitus have subjective tinnitus, or tinnitus that only you can hear. The noises of tinnitus may vary in pitch from a low roar to a high squeal, and you may hear it in one or both ears. In some cases, the sound can be so loud it interferes with your ability to concentrate or hear external sound. Tinnitus may be present all the time, or it may come and go.

In rare cases, tinnitus can occur as a rhythmic pulsing or whooshing sound, often in time with your heartbeat. This is called pulsatile tinnitus. If you have pulsatile tinnitus, your doctor may be able to hear your tinnitus when he or she does an examination (objective tinnitus).

When to see a doctor

Some people aren't very bothered by tinnitus. For other people, tinnitus disrupts their daily lives. If you have tinnitus that bothers you, see your doctor.

Make an appointment to see your doctor if:

• You develop tinnitus after an upper respiratory infection, such as a cold, and your tinnitus doesn't improve within a week.

See your doctor as soon as possible if:

• You have hearing loss or dizziness with the tinnitus.
• You are experiencing anxiety or depression as a result of your tinnitus.

Mayo Clinic Minute: Is tinnitus causing that ringing in your ear?

About 1 in 5 people experience the perception of noise or ringing in the ears. It's called tinnitus.

Dr. Gayla Poling says tinnitus can be perceived a myriad of ways. "Ninety percent of those with tinnitus have hearing loss." Hearing loss can be age-related, come from a one-time exposure, or exposure to loud sounds over a lifetime. Dr. Poling says the tiny hairs in our inner ear may play a role.

"Those little hair cells in our inner ear are really delicate structures. That's what is actually damaged with noise exposure."

Dr. Poling says there's no scientifically proven cure for tinnitus, but there are treatment and management options.

"Something as simple as getting a hearing aid to really treat the hearing loss." Other options include using a sound generator or using a fan at night.

"There's something called 'tinnitus retraining therapy.'" There are more ear-level masking devices where you can hear sounds throughout the day, too, that are more distracting."

If ringing in your ears bothers you, start by seeing your health care provider for a hearing test.

For the Mayo Clinic News Network, I'm Ian Roth.

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A number of health conditions can cause or worsen tinnitus. In many cases, an exact cause is never found.

Common causes of tinnitus

In many people, tinnitus is caused by one of the following:

Hearing loss. There are tiny, delicate hair cells in your inner ear (cochlea) that move when your ear receives sound waves. This movement triggers electrical signals along the nerve from your ear to your brain (auditory nerve). Your brain interprets these signals as sound.

If the hairs inside your inner ear are bent or broken — this happens as you age or when you are regularly exposed to loud sounds — they can "leak" random electrical impulses to your brain, causing tinnitus.

• Ear infection or ear canal blockage. Your ear canals can become blocked with a buildup of fluid (ear infection), earwax, dirt or other foreign materials. A blockage can change the pressure in your ear, causing tinnitus.
• Head or neck injuries. Head or neck trauma can affect the inner ear, hearing nerves or brain function linked to hearing. Such injuries usually cause tinnitus in only one ear.

Medications. A number of medications may cause or worsen tinnitus. Generally, the higher the dose of these medications, the worse tinnitus becomes. Often the unwanted noise disappears when you stop using these drugs.

Medications known to cause tinnitus include nonsteroidal anti-inflammatory drugs (NSAIDs) and certain antibiotics, cancer drugs, water pills (diuretics), antimalarial drugs and antidepressants.

Other causes of tinnitus

Less common causes of tinnitus include other ear problems, chronic health conditions, and injuries or conditions that affect the nerves in your ear or the hearing center in your brain.

• Meniere's disease. Tinnitus can be an early indicator of Meniere's disease, an inner ear disorder that may be caused by abnormal inner ear fluid pressure.
• Eustachian tube dysfunction. In this condition, the tube in your ear connecting the middle ear to your upper throat remains expanded all the time, which can make your ear feel full.
• Ear bone changes. Stiffening of the bones in your middle ear (otosclerosis) may affect your hearing and cause tinnitus. This condition, caused by abnormal bone growth, tends to run in families.
• Muscle spasms in the inner ear. Muscles in the inner ear can tense up (spasm), which can result in tinnitus, hearing loss and a feeling of fullness in the ear. This sometimes happens for no explainable reason, but can also be caused by neurologic diseases, including multiple sclerosis.
• Temporomandibular joint (TMJ) disorders. Problems with the TMJ , the joint on each side of your head in front of your ears, where your lower jawbone meets your skull, can cause tinnitus.
• Acoustic neuroma or other head and neck tumors. Acoustic neuroma is a noncancerous (benign) tumor that develops on the cranial nerve that runs from your brain to your inner ear and controls balance and hearing. Other head, neck or brain tumors can also cause tinnitus.
• Blood vessel disorders. Conditions that affect your blood vessels — such as atherosclerosis, high blood pressure, or kinked or malformed blood vessels — can cause blood to move through your veins and arteries with more force. These blood flow changes can cause tinnitus or make tinnitus more noticeable.
• Other chronic conditions. Conditions including diabetes, thyroid problems, migraines, anemia, and autoimmune disorders such as rheumatoid arthritis and lupus have all been associated with tinnitus.

Risk factors

Anyone can experience tinnitus, but these factors may increase your risk:

• Loud noise exposure. Loud noises, such as those from heavy equipment, chain saws and firearms, are common sources of noise-related hearing loss. Portable music devices, such as MP3 players, also can cause noise-related hearing loss if played loudly for long periods. People who work in noisy environments — such as factory and construction workers, musicians, and soldiers — are particularly at risk.
• Age. As you age, the number of functioning nerve fibers in your ears declines, possibly causing hearing problems often associated with tinnitus.
• Sex. Men are more likely to experience tinnitus.
• Tobacco and alcohol use. Smokers have a higher risk of developing tinnitus. Drinking alcohol also increases the risk of tinnitus.
• Certain health problems. Obesity, cardiovascular problems, high blood pressure, and a history of arthritis or head injury all increase your risk of tinnitus.

Complications

Tinnitus affects people differently. For some people, tinnitus can significantly affect quality of life. If you have tinnitus, you may also experience:

• Sleep problems
• Trouble concentrating
• Memory problems
• Anxiety and irritability
• Problems with work and family life

Treating these linked conditions may not affect tinnitus directly, but it can help you feel better.

More Information

• Tinnitus and antidepressants

In many cases, tinnitus is the result of something that can't be prevented. However, some precautions can help prevent certain kinds of tinnitus.

• Use hearing protection. Over time, exposure to loud sounds can damage the nerves in the ears, causing hearing loss and tinnitus. Try to limit your exposure to loud sounds. And if you cannot avoid loud sounds, use ear protection to help protect your hearing. If you use chain saws, are a musician, work in an industry that uses loud machinery or use firearms (especially pistols or shotguns), always wear over-the-ear hearing protection.
• Turn down the volume. Long-term exposure to amplified music with no ear protection or listening to music at very high volume through headphones can cause hearing loss and tinnitus.
• Take care of your cardiovascular health. Regular exercise, eating right and taking other steps to keep your blood vessels healthy can help prevent tinnitus linked to obesity and blood vessel disorders.
• Limit alcohol, caffeine and nicotine. These substances, especially when used in excess, can affect blood flow and contribute to tinnitus.
• AskMayoExpert. Non-pulsatile tinnitus. Mayo Clinic; 2019.
• Kellerman RD, et al. Tinnitus. In: Conn's Current Therapy 2021. Elsevier; 2021. https://www.clinicalkey.com. Accessed Dec. 22, 2020.
• Tunkel DE, et al. Clinical practice guideline: Tinnitus. Otolaryngology—Head and Neck Surgery. 2014; doi:10.1177/0194599814545325.
• Flint PW, et al., eds. Tinnitus and hyperacusis. In: Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Elsevier; 2021. https://www.clinicalkey.com. Accessed Dec. 22, 2020.
• Baguley D, et al. Tinnitus. The Lancet. 2013; doi:10.1016/S0140-6736(13)60142-7.
• Tinnitus. National Institute on Deafness and Other Communication Disorders. https://www.nidcd.nih.gov/health/tinnitus. Accessed Dec. 22, 2020.
• Dinces EA. Etiology and diagnosis of tinnitus. https://www.uptodate.com/contents/search. Accessed Dec. 22, 2020.
• Dinces EA. Treatment of tinnitus. https://www.uptodate.com/contents/search. Accessed Dec. 22, 2020.
• AskMayoExpert. Pulsatile tinnitus. Mayo Clinic; 2019.
• Causes. American Tinnitus Association. https://www.ata.org/understanding-facts/causes. Accessed Dec. 22, 2020.

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• Is tinnitus making you miserable? April 07, 2023, 01:30 p.m. CDT
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