long covid long covid long covid or long-haul covid (also known as post-covid-19 syndrome, post-covid-19 condition, post-acute sequelae of covid-19 (pasc), or chronic covid syndrome (ccs)) is a condition characterized by long-term, multi-system, often severe health problems persisting or appearing after the typical recovery period of covid-19. although studies into long covid are under way, as of may 2022 there is no consensus on the definition of the term. part of a series on thecovid-19 pandemicscientifically accurate atomic model of the external structure of sars-cov-2. each "ball" is an atom. covid-19 (disease) sars-cov-2 (virus) cases deaths timeline 2019 2020 january responses february responses march responses april responses may responses june responses july responses august responses september responses october responses november responses december responses 2021 january responses february responses march responses april responses may responses june responses july responses 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by country disability domestic violence emergency evacuations education female environment hospitals language lgbt community long-term care media coverage mental health symptoms migration military notable deaths other health issues politics diplomacy popular culture protests pregnancy prisons religion catholic church hajj science and technology social media strikes suicides telehealth xenophobia and racism society ireland malaysia new zealand russia uk us covid-19 portal long covid may affect multiple organ systems, including disorders of the respiratory, cardiovascular, gastrointestinal and nervous systems, mental health, metabolism, musculoskeletal pain, anemia and exercise intolerance/ post-exertional malaise the most commonly reported symptoms of long covid are fatigue and memory problems. many other symptoms have also been reported, including malaise, headaches, shortness of breath, anosmia (loss of smell), parosmia (distorted smell), ageusia (distortion or loss of taste), muscle weakness, low-grade fever, and cognitive dysfunction. estimates of the prevalence of long covid vary based on definition, population studied, time period studied, and methodology, generally ranging between 5% and 50%. health systems in some countries and jurisdictions have been mobilized to deal with this group of patients by creating specialized clinics and providing advice. as of 2022, there are no tests or biomarkers to diagnose long covid and no therapies to treat it. overall, it is considered by default to be a diagnosis of exclusion. in march 2023, treatment with nirmatrelvir within 5 days of initial infection was shown to reduce risk of long covid. terminology and definitions overview long covid is a patient-created term which was reportedly first used in may 2020 as a hashtag on twitter by elisa perego, an archaeologist at university college london. long covid has no single, strict definition. it is normal and expected that people who experience severe symptoms or complications such as post-intensive care syndrome or secondary infections will take longer to recover than people who did not require hospitalization (called mild covid-19) and had no such complications. it can be difficult to determine whether an individual's set of ongoing symptoms represents a normal, prolonged convalescence, or extended 'long covid'. one rule of thumb is that long covid represents symptoms that have been present for longer than two months, though there is no reason to believe that this choice of cutoff is specific to infection with the sars-cov-2 virus. world health organization clinical case definition the world health organization (who) established a clinical case definition in october 2021, published in the journal the lancet infectious diseases: post-covid-19 condition occurs in individuals with a history of probable or confirmed sars-cov-2 infection, usually 3 months from the onset, with symptoms that last for at least 2 months and cannot be explained by an alternative diagnosis. common symptoms include, but are not limited to, fatigue, shortness of breath, and cognitive dysfunction, and generally have an impact on everyday functioning. symptoms might be new onset following initial recovery from an acute covid-19 episode or persist from the initial illness. symptoms might also fluctuate or relapse over time. british definition the british national institute for health and care excellence (nice) divides covid-19 into three clinical case definitions: acute covid-19 for signs and symptoms during the first four weeks after infection with severe acute respiratory syndrome coronavirus 2 (sars-cov-2) is the first, and long covid for new or ongoing symptoms four weeks or more after the start of acute covid-19, which is divided into the other two: ongoing symptomatic covid-19 for effects from four to twelve weeks after onset, and post-covid-19 syndrome for effects that persist 12 or more weeks after onset. nice describes the term long covid, which it uses "in addition to the clinical case definitions", as "commonly used to describe signs and symptoms that continue or develop after acute covid-19. it includes both ongoing symptomatic covid-19 (from four to twelve weeks) and post-covid-19 syndrome (12 weeks or more)". nice defines post-covid-19 syndrome as "signs and symptoms that develop during or after an infection consistent with covid‑19, continue for more than 12 weeks and are not explained by an alternative diagnosis. it usually presents with clusters of symptoms, often overlapping, which can fluctuate and change over time and can affect any system in the body. post‑covid‑19 syndrome may be considered before 12 weeks while the possibility of an alternative underlying disease is also being assessed". american definition in february 2021, the u.s. national institutes of health (nih) director francis collins indicated long covid symptoms for individuals who "don't recover fully over a period of a few weeks" be collectively referred to as "post-acute sequelae of sars-cov-2 infection" (pasc). the nih listed long covid symptoms of fatigue, shortness of breath, brain fog, sleep disorders, intermittent fevers, gastrointestinal symptoms, anxiety, and depression. symptoms can persist for months and can range from mild to incapacitating, with new symptoms arising well after the time of infection. the centers for disease control and prevention (cdc) term post-covid conditions qualifies long covid as symptoms four or more weeks after first infection. symptoms a scientific review identified over 50 apparent long-term effects – including those of 'long covid' – along with their estimated prevalence and estimated that 80% of included patients had at least one overall effect beyond two weeks. external video “long covid: a parallel pandemic”, akiko iwasaki and others, knowable magazine, 8 august 2022. long covid symptoms may involve multiple organs and may be severe. recovery from symptoms may take longer than 35 weeks for most people affected, and may vary over time, with fatigue, post-exertional malaise and cognitive deficits as the most common symptoms after six months. symptom relapse occurred in 86% of adult participants triggered by physical or mental effort or by stress. three groups of symptoms were identified: initial symptoms that peak in the first two to three weeks and then subside; stable symptoms; and symptoms that increase markedly in the first two months and then stabilize. symptoms reported by adults with long covid include: fatigue, including extreme fatigue substantial exercise intolerance more than 3 months after infection; postexertional malaise similar to that which is the hallmark of chronic fatigue syndrome long-lasting cough muscle weakness low-grade fever inability to concentrate (brain fog) memory lapses mental health problems, such as changes in mood or depression sleep difficulties headaches joint pain prickling pain (paresthesia) in hands and feet diarrhea bouts of vomiting loss of, or changes in, sense of smell (anosmia or parosmia) loss of or changes in sense of taste (dysgeusia) sore throat and or difficulties swallowing circulation disorders, including new onsets of diabetes and hypertension heartburn (gastroesophageal reflux disease) skin rash shortness of breath chest pains palpitations kidney problems (including, acute kidney injury and chronic kidney disease) changes in oral health (teeth, saliva, gums) tinnitus hearing loss blood clotting (including deep vein thrombosis and pulmonary embolism) erectile dysfunction one study of 35,000 patients with long covid symptoms found cases clustered into four major symptom patterns: subphenotype 1 (cardiac and renal), representing about 34% of people was dominated by cardiac-related, kidney-related and circulation-related issues, including cardiac and circulatory conditions, renal failure, anemia and fluid and electrolyte disorders. subphenotype 2 (respiratory, sleep and anxiety) representing 33% people was dominated by respiratory conditions, sleep disorders, anxiety and symptoms such as headache and chest pain. subphenotype 3 (musculoskeletal and nervous) consisted of 23% people who had musculoskeletal and nervous system sequelae, such as musculoskeletal pain, headaches and sleep-wake disorders. subphenotype 4 (digestive and respiratory) included 10% people who mainly had digestive system and respiratory conditions, including abdominal pain, breathing abnormalities and throat or chest pain, anemia and nausea or vomiting. a retrospective cohort study of 1,913,234 maccabi healthcare services members found that covid-19 infection was significantly associated with increased risk for anosmia and dysgeusia, cognitive impairment, dyspnoea, weakness, and palpitations, with significant but lower risk for streptococcal tonsillitis and dizziness, during both the early and late phase of the disease. the study, which was conducted between 1 march 2020 and 1 october 2021, analyzed long-term health outcomes among people infected with wild-type sars-cov-2, the alpha variant, and the delta variant; the study suggested that most people who present with long covid sequelae recover within a year of diagnosis. epidemiology estimates of the prevalence of long covid vary widely. the estimates depend on the definition of long covid and the population studied. an april 2022 meta-analysis estimated that the pooled prevalence of post-covid conditions was 43%, with estimates ranging between 9% and 81%. people who had been hospitalised with covid saw a higher prevalence of 54%, while this number dropped to 34% for nonhospitalised people. prevalence generally decreased with a longer follow-up time. in people age 0–18 years the prevalence of long covid conditions – like mood symptoms, cfs and sleep disorders – appears to be at ~25% overall. in a large population cohort study in scotland, 42% of respondents said they had not fully recovered after 6 to 18 months after catching covid, and 6% indicated they had not recovered at all. the risk of long covid was associated with disease severity; people with asymptomatic infection did not have increased risk of long covid symptoms compared to people who had never been infected. those that had been hospitalised had 4.6 times higher odds of no recovery compared to nonhopitalised people. in june 2022, a cdc study based on electronic health records showed that "one in five covid-19 survivors aged 18–64 years and one in four survivors aged ≥65 years experienced at least one incident condition that might be attributable to previous covid-19" or long covid. an analysis of private healthcare claims showed that of 78,252 patients diagnosed with 'long covid', 75.8% had not been hospitalized for covid-19. children long covid is uncommon in children and their features differ from adults: in a retrospective cohort study from october 2022 of almost 660,000 us children tested for sars-cov-2 by antigen or polymerase chain reaction, the incidence of at least 1 systemic, syndromic, or medication feature of long covid (1-6 months afterwards) was 42% among viral test–positive children versus 38%