Long Covid

Long COVID, also known as chronic COVID syndrome (CCS) and long-haul COVID, is an informal name for the condition characterised by long-term sequelae—persisting after the typical convalescence period—of coronavirus disease 2019 (COVID-19). Persistent symptoms include fatigue, headaches, shortness of breath, anosmia (loss of smell), muscle weakness, low fever and cognitive dysfunction (brain fog).

About 10% of people who have tested positive for SARS-CoV-2 experience a range of symptoms that last longer than three weeks. About 2% of people report having symptoms which last longer than 12 weeks, which is called post-COVID-19 syndrome. Sufferers of long COVID are sometimes called long-haulers.

Studies are under way into various aspects of long COVID, but as of December 2020^[update] it is too early to draw conclusions, although one study has suggested risk factors for developing the illness. Health systems in some countries or jurisdictions have been mobilised to deal with this group of patients by creating specialised clinics and providing advice.

Anyone infected with SARS-CoV-2 can suffer from "long COVID" after the infection is considered to have ended, including young, healthy people, and even if the initial disease at its peak only caused minor symptoms. The risk of long COVID for patients of any age, in addition to the age-dependent risk of serious illness or death during the acute phase, makes it important to prevent coronavirus infection and master the pandemic through measures including social distancing, use of face masks, and of personal protective equipment by those working with patients, hand cleaning, and vaccination.

While "Long COVID" is observed after acute COVID-19, it had not been reported after vaccination, with over 100,000 participants included in vaccine trials by December 2020.

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.

Sufferers are often referred to as long-haulers.

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.

British definition

The British National Institute for Health and Care Excellence (NICE) divides COVID-19 into three clinical definitions:

• acute COVID-19 for signs and symptoms during the first 4 weeks after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2),
• new or ongoing symptoms 4 weeks or more after the start of acute COVID-19, which is divided into:
  • ongoing symptomatic COVID-19 for effects from 4 to 12 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 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".

Incidence

As time passed, from the first reports of the disease in December 2019 through the spread of the COVID-19 pandemic into 2020, it started becoming clear that COVID-19 was a long-term illness for many people, seen in people who had a mild or moderate initial infection as well as those who were admitted to hospital with more severe infection.

Some early studies suggested that between 1 in 5 and 1 in 10 people with COVID-19 experienced symptoms lasting longer than a month. Early studies usually tracked people who had been hospitalized for severe COVID, and whose recovery was longer. Among the general population, about 90% of people stop reporting symptoms after about three weeks, and about 10% continue to report significant symptoms. Different studies continue to report different rates.

A case report and systematic review from Sweden has suggested that long COVID may also occur in children. Common symptoms in children were fatigue, dyspnoea, heart palpitations or chest pain, and there seemed to be a female predominance.

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 September 2020 study by King's College, London suggested the incidence in the UK was up to 60,000, but statistics published in December by the Office of National Statistics suggest that as many as one in five patients are afflicted with long-term symptoms (although these statistics only report post-COVID and not pre-COVID incidence of those symptoms, which may have been pre-existent).

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%).

Cause

No one knows why most people recover fully within two to three weeks and others experience symptoms for weeks or months longer. An early analysis by the United Kingdom's National Institute for Health Research suggests that ongoing long COVID symptoms may be due to four syndromes:

• permanent damage to the lungs and heart,
• post-intensive care syndrome,
• post-viral fatigue syndrome, and
• continuing COVID-19 symptoms.

Other situations that might cause new and ongoing symptoms include:

• the virus being present for a longer time than usual, due to an ineffective immune response;
• reinfection (e.g., with another strain of the virus);
• damage caused by inflammation and a strong immune response to the infection;
• physical deconditioning due to a lack of exercise while ill; and
• post-traumatic stress or other mental sequelae, especially in people who had previously experienced anxiety, depression, insomnia, or other mental health difficulties.

Long COVID is similar to post-Ebola syndrome and the post-infection syndromes seen in chikungunya and the infections that appear to trigger myalgic encephalomyelitis (ME, aka chronic fatigue syndrome), and the pathophysiology of long COVID may be similar to these other conditions.

Risk factors

According to a King's College London study initially posted on 21 October 2020 risk factors for long COVID may include:

• Age – particularly those aged over 50
• Excess weight
• Asthma
• Reporting more than five symptoms (e.g. more than cough, fatigue, headache, diarrhoea, loss of sense of smell) in the first week of COVID-19 infection; five is the median number reported

Women and girls are less likely to develop severe acute COVID but more likely to develop long COVID than men and boys. This is unlikely to be due primarily to hormonal differences, but other factors, including chromosomal genetics, sex-dependent differences in immune system behavior, and non-biological factors may be relevant.

Health system responses

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.

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.

Public response

Some people experiencing long COVID have formed groups on social media sites. 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:

See also

• Post viral cerebellar ataxia – clumsy movement appearing a few weeks after a viral infection
• Post-polio syndrome – delayed reaction appearing years after acute polio infection resolves
• Post-Ebola virus syndrome – symptoms that persist after recovering from Ebola