Long COVID

Long COVID, also known as post-acute sequelae of SARS-CoV-2 infection, post-acute sequelae of COVID-19 (PASC), chronic COVID syndrome (CCS) and long-haul COVID, is a condition characterized by long-term sequelae—persisting after the typical convalescence period—of coronavirus disease 2019 (COVID-19). Long covid can affect nearly every organ system with sequelae including respiratory system disorders, nervous system and neurocognitive disorders, mental health disorders, metabolic disorders, cardiovascular disorders, gastrointestinal disorders, malaise, fatigue, musculoskeletal pain, and anemia. A wide range of symptoms are commonly discussed, including fatigue, headaches, shortness of breath, anosmia (loss of smell), parosmia (distorted smell), muscle weakness, low fever and cognitive dysfunction.
The exact nature of symptoms and number of people who experience long-term symptoms is unknown and varies according to the population being studied, the definition used, and the time period used in the study. A preliminary survey by the UK Office of National Statistics estimated that approximately 10% of people who tested positive for SARS-CoV-2 experienced one or more symptoms for longer than 12 weeks.
While studies into various aspects of long COVID are under way, , the definition of the illness is still unclear and it is too early to draw conclusions on the mechanism. Health systems in some countries or jurisdictions have been mobilized to deal with this group of patients by creating specialized clinics and providing advice. Nonetheless, the illness is not well-characterized, has no understood mechanism nor fixed diagnostic citeria, and therefore is considered an idiopathic disease, and a diagnosis of exclusion.
Some believe that it is possible that anyone infected with SARS-CoV-2 may suffer from long COVID after the infection is considered to have ended. For example, a widely-publicized study in 2020 suggested that SARS-CoV-2 infection led to cardiac inflammation in a survey of student athletes, however, other researchers have subsequently cast doubt on this claim, suggesting that the findings may be due to diagnostic bias or confusion with other conditions.
While long COVID is observed after COVID-19 infection, it has not been reported after COVID-19 vaccination, with over 100,000 participants included in vaccine trials .
Terminology and definitions.
"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 naturally take longer to recover than people who had mild illness and no such complications. This natural variation can make it difficult to determine whether a specific individual's set of ongoing symptoms represent a fundamentally normal, if long, convalescence, or if long COVID is present. 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.
British definition.
The British National Institute for Health and Care Excellence (NICE) divides COVID-19 into three clinical definitions:
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 4 to 12 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".
U.S. definition.
In February 2021, the National Institutes of Health said symptoms of Long COVID can include 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. NIH Director Francis Collins said the condition can be collectively referred to as Post-Acute Sequelae of SARS-CoV-2 infection (PASC).
Incidence.
Some reports of long-term illness after infection appeared early during the COVID-19 pandemic, including in people who had a mild or moderate initial infection as well as those who were admitted to hospital with more severe infection.
, the precise incidence was unknown. The incidence declines over time, as many people slowly recover. Some early studies suggested that between 20% and 33% of people with COVID-19 experienced symptoms lasting longer than a month. A telephone survey in the US in the first half of 2020 showed that about 35% of people who had tested positive for SARS-CoV-2 experienced a range of symptoms that lasted longer than three weeks. As of December 2020, the Office of National Statistics in the UK estimated that, of all people with a positive test for SARS-CoV-2, about 21% experienced symptoms for longer than five weeks, and about 10% experienced symptoms for longer than 12 weeks.
Some studies have suggested that some children experience lingering symptoms of SARS-CoV-2 infection.
Although anyone who gets infected can develop long COVID, people who become so sick that they require hospitalization take longer to recover. A majority (up to 80%) of those who were admitted to hospital with severe disease experience long-term problems including fatigue and shortness of breath (dyspnoea). Patients with severe initial infection, particularly those who required mechanical ventilation to help breathing, are also likely to suffer from post-intensive care syndrome following recovery. A study of patients who had been hospitalised in Wuhan found that the majority still had at least one symptom after six months. Patients who had been more severely ill still showed severe incapacity in lung function. Among the 1733 patients who had been discharged from hospital and followed up about six months later, the most common symptoms were fatigue or muscle weakness (63%), sleep difficulties (26%), and anxiety or depression (23%).
Some people suffer long-term neurologic symptoms despite never having been hospitalized for COVID-19; the first study of this population was published in March 2021. Most frequently, these non-hospitalized patients experienced "prominent and persistent 'brain fog' and fatigue that affect their cognition and quality of life."
In January 2021, a study in the UK reported that 30% of recovered patients were readmitted to hospital within 140 days, and 12% of the total died. Many patients had developed diabetes for the first time, as well as problems with heart, liver and kidney problems. The mode of insulin failure was at that point unknown.
In March 2021, the Indonesian Doctors Association, in a survey of 463 people, suggested that 63.5% of respondents self-reported lingering symptoms after SARS-CoV-2 infection. The exact set of symptoms was not specified, however, according to the article, fatigue and cough were the most commonly reported symptoms, followed by muscle pain and headache.
Cause.
It is currently unknown why most people recover fully within two to three weeks and others experience symptoms for weeks or months longer. A review by the United Kingdom's National Institute for Health Research hypothesized that ongoing long COVID symptoms may be due to four syndromes:
Other situations that might cause new and ongoing symptoms include:
Similarities to other syndromes.
Long COVID is similar to post-Ebola syndrome and the post-infection syndromes seen in chikungunya and the infections that appear to trigger ME/CFS, and the pathophysiology of long COVID may be similar to these other conditions. Some long COVID patients in Canada have been diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome, a "debilitating, multi-system neurological disease that is believed to be triggered by an infectious illness in the majority of cases". Lucinda Bateman, a specialist in ME/CFS in Salt Lake City in the US believes that the two syndromes are identical. There is need for more research into ME/CFS; Anthony Fauci, chief medical adviser to the US government, said that COVID-19 is a "well-identified etiologic agent that should be very helpful now in getting us to be able to understand [ME/CFS]”.
Risk factors.
According to a King's College London study initially posted on 21 October 2020 risk factors for long COVID may include:
Women are less likely to develop severe acute COVID but more likely to develop long COVID than men. Some research suggests this is due primarily to hormonal differences, while other research points to other factors, including chromosomal genetics, sex-dependent differences in immune system behavior, and non-biological factors may be relevant.
In children.
A study in Italy, which analyzed 129 children under the age of 18, examined health data obtained via a questionnaire between September 2020 and January 1, 2021. 53% of the group experienced COVID-19 symptoms more than 120 days after their diagnosis. Symptoms included chest tightness and pain, nasal congestion, tiredness, difficulty concentrating and muscle pain. A case report of 5 children in Sweden also reported symptoms (fatigue, heart palpitations, dyspnoea, headaches, muscle weakness and difficulty concentrating) persisting for 6–8 months after diagnosis.
Health system responses.
United States.
Dr. Anthony S. Fauci has described long-term COVID-19 as “...a phenomenon that is really quite real and quite extensive,” but also said that the number of cases is unknown.
On February 23, 2021, National Institutes of Health Director Francis Collins announced a major initiative to identify the causes and ultimately the means of prevention and treatment of people who are suffering from long COVID. Part of this initiative includes the creation of the COVID-19 Project, which will gather data on neurological symptoms associated with PASC.
On April 28, 2021, the Subcommittee on Health of the U.S. House of Representatives' Committee on Energy and Commerce held a hearing about long COVID.
Australia.
In October 2020, a guide published by the Royal Australian College of General Practitioners (RACGP) says that ongoing post-COVID-19 infection symptoms such as fatigue, shortness of breath and chest pain will require management by GPs, in addition to the more severe conditions already documented.
United Kingdom.
In Britain, the National Health Service set up specialist clinics for the treatment of long COVID. The four Chief Medical Officers of the UK were warned of academic concern over long COVID on 21 September 2020 in a letter written by Trisha Greenhalgh published in "The BMJ" signed by academics including David Hunter, Martin McKee, Susan Michie, Melinda Mills, Christina Pagel, Stephen Reicher, Gabriel Scally, Devi Sridhar, Charles Tannock, Yee Whye Teh, and Harry Burns, former CMO for Scotland. In October 2020, NHS England's head Simon Stevens announced the NHS had committed £10 million to be spent that year on setting up long COVID clinics to assess patients' physical, cognitive, and psychological conditions and to provide specialist treatment. Future clinical guidelines were announced, with further research on 10,000 patients planned and a designated task-force to be set up, along with an online rehabilitation service – "Your Covid Recovery". The clinics include a variety of medical professionals and therapists, with the aim of providing "joined-up care for physical and mental health”.
The National Institute for Health Research has allocated funding for research into the mechanisms behind symptoms of Long COVID.
In December 2020, University College London Hospitals (UCLH) opened a second Long Covid clinic at the National Hospital for Neurology and Neurosurgery for patients with post-Covid neurological issues. The first clinic had opened in May, primarily focused on respiratory problems, but both clinics refer patients to other specialists where needed, including cardiologists, physiotherapists and psychiatrists. By March 2021 there were 69 long covid clinics in the English NHS. mostly focussing on assessing patients, with more planned to open. There were fears that community rehabilitation services did not have capacity to manage large numbers of referrals.
On 18 December 2020, the National Institute for Health and Care Excellence (NICE), the Royal College of General Practitioners (RCGP) and the Scottish Intercollegiate Guidelines Network (SIGN) published a guide to the management of Long COVID.
South Africa.
In October 2020, the DATCOV Hospital Surveillance Department of the National Institute for Communicable Diseases (NICD) looked into a partnership with the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC) in order to conduct clinical research into the impact PASC may have within the South African Context. As of the 30th of January 2021, the project has yet to receive ethical approval for the commencement of data collection. Ethics approval was granted on the 3rd of February 2021 and formal data collection began on the 8th of February 2021.
Public response.
Some people experiencing long COVID have formed groups on social media sites. There is an active international long COVID patient advocacy movement which includes research led by patients themselves.
In many of these groups, individuals express frustration and their sense that their problems have been dismissed by medical professionals.
List of symptoms.
Symptoms reported by people with long COVID include: