What is long covid
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Understanding Long COVID: Symptoms, Prevalence, and Pathophysiology
Definition and Terminology of Long COVID
Long COVID refers to the persistence of symptoms in individuals who have recovered from the acute phase of SARS-CoV-2 infection. This condition is also known as "post-COVID-19 condition" or "COVID long-haulers"1 4. The term encompasses a wide range of symptoms that continue for weeks or even months after the initial infection, regardless of the severity of the initial illness7 9.
Common Symptoms of Long COVID
Physical Symptoms
The most frequently reported symptoms of Long COVID include fatigue, breathlessness, chest pain, and myalgia. Other common symptoms are cough, chest tightness, palpitations, and difficulty focusing1 2 5. Studies have shown that fatigue is the most prevalent symptom, affecting up to 58% of patients, followed by headache (44%), and dyspnea (24%)6.
Psychological and Neurological Symptoms
Long COVID also manifests with psychological and neurological symptoms such as concentration impairment, attention disorders, and olfactory and gustatory dysfunctions2 3 6. These symptoms can significantly impact the quality of life, with around 37% of patients reporting a reduced quality of life3.
Prevalence and Risk Factors
Incidence Rates
The prevalence of Long COVID varies widely across studies, with estimates ranging from 0% to 93% depending on the population and methods used10. A meta-analysis found that approximately 80% of patients who had COVID-19 developed one or more long-term symptoms6.
Risk Factors
Several factors increase the likelihood of developing Long COVID. These include older age, higher body mass index, and female sex. Experiencing more than five symptoms during the first week of illness is also associated with a higher risk of Long COVID8.
Pathophysiology of Long COVID
Organ Damage and Immune Dysregulation
The underlying mechanisms of Long COVID are not fully understood, but it is believed to result from long-term organ damage due to the acute phase of the infection. Immune dysregulation, auto-immunity, endothelial dysfunction, and occult viral persistence are also considered significant contributors7.
Autonomic Nervous System Damage
Damage to the autonomic nervous system may account for many symptoms without clear evidence of organ damage. This can lead to a range of symptoms affecting multiple organ systems7.
Clinical Management and Future Directions
Diagnostic Challenges
The heterogeneity of symptoms and the lack of a standardized definition make diagnosing Long COVID challenging. Clinical evaluation should focus on identifying the pathophysiology to guide appropriate remedial measures1 4.
Need for Multidisciplinary Approach
Given the complex nature of Long COVID, a multidisciplinary approach involving various specialties is crucial for effective management. This includes developing preventive measures, rehabilitation techniques, and clinical management strategies6.
Research Gaps
There is an urgent need for prospective, robust, and standardized studies to better understand the aetiology, risk factors, and biomarkers of Long COVID. Such research will help in characterizing the condition in different at-risk populations and settings3 7.
Conclusion
Long COVID is a multifaceted condition with a wide range of symptoms that can persist long after the acute phase of SARS-CoV-2 infection. Understanding its prevalence, risk factors, and underlying mechanisms is crucial for developing effective management and rehabilitation strategies. Further research is needed to provide a clearer picture and improve outcomes for those affected by this condition.
Sources and full results
Most relevant research papers on this topic
Long COVID: An overview
Long COVID symptoms include fatigue, cough, chest tightness, breathlessness, palpitations, myalgia, and difficulty to focus, and should be managed by identifying the pathophysiology and appropriate remedial measures.
Systematic Review
Highly CitedSymptoms and signs of long COVID: A rapid review and meta-analysis
Long COVID symptoms include fatigue, dyspnea, olfactory dysfunction, myalgia, cough, and gustatory dysfunction, with high heterogeneity in meta-analysis affecting pooled incidence estimates.
Meta-Analysis
Rigorous JournalCharacterising long COVID: a living systematic review
Long COVID is a complex condition with prolonged heterogeneous symptoms, requiring further prospective, robust, standardised, controlled studies to better understand its aetiology, risk factors, and biomarkers.
Systematic ReviewRigorous JournalHighly CitedLong COVID: current definition
Long COVID definition is currently unclear, with no consensus on the appropriate terminology for chronic post-COVID symptoms, and the need for improved recognition and management of this condition.
Systematic ReviewLong COVID, a comprehensive systematic scoping review
Long COVID has controversies in definition, with predominant symptoms including fatigue, breathlessness, arthralgia, sleep difficulties, and chest pain, and potential long-term health complications.
Systematic ReviewHighly CitedMore than 50 long-term effects of COVID-19: a systematic review and meta-analysis
80% of COVID-19 patients develop one or more long-term symptoms, with fatigue, headache, attention disorder, hair loss, and dyspnea being the most common.
Meta-AnalysisRigorous JournalHighly CitedPathophysiology and mechanism of long COVID: a comprehensive review
Long COVID symptoms may result from long-term organ damage and specific mechanisms following acute illness, with the underlying pathophysiology still unclear.
Systematic ReviewHighly CitedAttributes and predictors of long COVID
Long COVID symptoms, characterized by fatigue, headache, dyspnea, and anosmia, are more likely with increasing age, BMI, and female sex, and a simple model can identify individuals at risk early in the disease.
Observational StudyRigorous JournalHighly CitedWhy the Patient-Made Term 'Long Covid' is needed
The patient-made term 'Long Covid' is crucial for addressing medical, epidemiological, and socio-political challenges posed by diverse symptoms persisting beyond four weeks after symptom onset in COVID-19 patients.
Rigorous JournalHighly CitedSystematic Review of the Prevalence of Long COVID
Long COVID prevalence estimates vary, but the burden of chronic illness due to SARSCoV2 infection is likely substantial, even using conservative estimates.
Systematic ReviewRigorous Journal