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July 1, 2021
Coronavirus Update FAQ 12
October 7, 2021

Coronavirus Update FAQ 11


Long-term effects of acute Covid 19 infection - The Long Covid Syndrome

Stefan Lindgren, Ramon Pujol (writers) and Chris Davidson (corrector)

Although the knowledge about acute Covid 19 infection has increased dramatically, many questions remain unanswered. Why is the infection mild or even without symptoms in the majority while it may be severe, requiring hospitalisation, intensive care or even be fatal in others? What is the explanation for loss of smell and taste in quite a few of the infected individuals, a complication seldom seen in other acute infections? Now we also realise that many people suffer long-term and sometimes debilitating symptoms, following Covid19 infection, the so called Long Covid syndrome. Accumulating data suggest that these patients may experience a wide range of symptoms after recovery from acute illness. But we still lack knowledge to predict which patients are at risk for Long Covid.

Who is at risk?

Extended periods with fatigue, muscle and joint pain and mental tiredness after acute infections in some individuals have been documented for many different types of mainly viral infections. Such protracted disease courses have been known for decades and were often previously referred to as “postinfectious asthenia”. However, the magnitude of the problem has been highlighted during the Covid 19 pandemic. As with Covid 19 infection generally, it is difficult to identify major risk factors for Long Covid Syndrome after acute Covid 19 infection. However, it is evident that individuals who required hospital care for their acute infection are at higher risk than those who did not need admission to hospital. Thus, an association with severity of the acute infection is likely. Furthermore, the risk for Long Covid seems to be higher in younger individuals. Since shortness of breath is a frequent symptom among those with persistent symptoms, pre-existing chronic lung disease has been identified as another risk factor.

What are the symptoms?

Cough, shortness of breath, fatigue and exhaustion and sleep disturbances are the commonest long-term symptoms after the acute phase of Covid 19 infection. Loss of smell and taste, impaired concentration and decreased cognitive functions, often referred to by patients as “brain fog” as well as joint and muscle pain are often reported. Usually, the severity of the symptoms decreases with time, but longer-follow-up is needed to establish the risk for a chronic condition. Even so, the consequences for health associated functioning and quality of life may be substantial. The mechanisms behind this broad and varied spectrum of symptoms are still largely unknown, although spread of virus through nerves involved in smelling to the brain may contribute to cognitive symptoms.

How big is the risk?

In several large compilations of many smaller studies, the occurrence of at least one remaining symptom among patients who were hospitalised during the acute infection is 60 % six months later. Among individuals who did not need hospital care, the frequency appears to be lower. But again, longer follow-up is necessary before the true situation is uncovered. Early data suggested a longer recovery course in patients requiring hospitalization, older patients with pre-existing comorbidities, patients who experienced medical complications (e.g., secondary bacterial pneumonia, venous thromboembolism), and patients who had a prolonged stay in the hospital or Intensive Care Unit. However, subsequent data suggest that even patients with less severe disease who were never hospitalized, including those with self-reported COVID 19, often experience prolonged and persistent symptoms.

Follow-up of symptoms

Fatigue, weakness, and poor endurance. Although the fatigue resolves in most patients, it can be profound and may last for three months or longer, particularly among survivors from Intensive Care Units.

Dyspnea. The shortness of breath may persist, resolving slowly in most patients over two to three months, sometimes longer.

Chronic cough. In several studies, many patients experienced persistent cough during two to three weeks following initial symptoms. Cough resolved in the majority of patients within three months.

Chest discomfort. Among patients with COVID19, chest discomfort is common and may resolve slowly. Chest discomfort persists in 12 to 22 percent of patients approximately two to three months after acute COVID 19 infection.

Altered taste and smell. The majority have complete or near-complete recovery one month following acute illness.

In a retrospective study of over 100,000 patients admitted to United States hospitals with COVID19, 9 percent among those who were discharged were readmitted to hospital within two months. Among those readmitted, 1.6 percent had multiple hospital readmissions.

What can be done?

General medical care and support, including diagnosis of associated diseases is key to improvement. Relearning of the sense of smelling and the ability to identify different smells has been successful. In many countries, specified outpatient clinics devoted to post Covid symptoms have been set up. Special attention is paid to supporting function, improve quality of life and work-place related rehabilitation.


  • Long Covid is a reality, but mainly for those who had a severe acute infection
  • Severe sequelae seem to be rare
  • There is no specific treatment
  • Vaccination offers the best protection for Long Covid

The Foundation for the Development of Internal Medicine (FDIME),

Daniel Sereni, Ramon Pujol, Jan Willem Elte.

With the help of Imad Hatem, Nica Cappellini, Lorenzo Dagna, Chris Davidson, Runolfur Palsson, Stefan Lindgren, Vereny Briner, Werner Bauer (in random order).