On the frequency and causes of prolonged covid symptoms.
Approximately 10% of people with symptomatic SARS-CoV-2 infection report persistent or recurring covid symptoms for several weeks or months. This notably includes younger and previously healthy individuals, as well as those whose original covid was mild or moderate (without hospitalization).
A small study by the US Center for Disease Control (CDC) found that up to 30% of non-hospitalized covid patients still experience typical symptoms after about one month. Among 18- to 35-year-olds without pre-existing conditions, the figure was still around 20%.
(Update: According to the latest British ONS survey, close to 14% of PCR-confirmed people (hospitalization rate 8%) reported symptoms lasting longer than three months (compared to 2% in the control group), of which about 60% reported “some limitation” and close to 20% “strong limitation” to their day-to-day activities. According to another British study based on somewhat different criteria, only 2% had symptoms lasting longer than three months.)
Frequently reported symptoms include persistent coughing, moderate fever, general fatigue or exhaustion, shortness of breath, chest pain, heart palpitations, headaches, concentration problems, muscle pain, digestive problems, skin rashes and metabolic symptoms.
The exact cause of these persistent symptoms is not yet clear; cardiological (heart), endothelial (blood vessels), pulmonary (lungs), neurological (nerves), renal (kidneys) or metabolic factors are suspected to play a role and may be triggered by the viral infection or the immune response to it. Repeated occurrence and subsiding of the symptoms is also frequently reported. Some researchers suspect that auto-immune reactions may play a role in long covid.
Some affected persons, including young people from around 30 years of age, report significant restrictions in their everyday life, such as exhaustion after climbing stairs or extended walks, as well as psychological effects such as despair or depression.
One to two months after coronavirus infection, symptomatic Swiss army recruits (median age 21 years) still showed a reduction of up to 20% in their maximum lung performance. The cause for such a reduction in lung performance likely is covid-induced pneumonia.
Initial studies found involvement of the heart muscle (myocarditis) in a considerable proportion of mild and moderate covid cases. People with persistent chest pain or other persistent or new symptoms are therefore advised to consult a doctor for an assessment.
(Update: A British study with 200 long covid patients found mild myocarditis in about 10% of them. This value is significantly lower than originally assumed and comparable to influenza virus infections. Several covid autopsy studies have also found little evidence of myocarditis. In February 2021, cardiologist Donald Llyod-Jones, president-elect of the American Heart Association, stated that “there’s a lot less myocarditis than we originally thought there would be.”)
The so-called post-viral syndrome or post-viral fatigue is already known from other viral infections, including severe influenza (flu). The involvement of the heart muscle is also known from strong and pandemic influenza. The occurrence of post-acute covid is therefore not surprising or unusual, but it is nevertheless quite widespread and must be taken very seriously.
Many people affected by long covid report a slow, wave-like improvement of symptoms, but an evidence-based medical prognosis is not yet possible at present. In any case, British doctors are predicting that there will be important public health questions related to post-acute covid.
On the other hand, German lung specialists and Swiss heart specialists reported significant regeneration within three months even in previously hospitalized covid patients. British doctors reported that 75% of hospitalized patients still exhibited symptoms after three months, but with most patients improving and showing no permanent lung tissue damage.
In order to avoid post-acute covid completely, infection with the virus must be avoided. If a symptomatic infection does occur, early treatment options should be discussed with a physician to prevent progression of the disease. For the large majority of the population, covid nevertheless remains a comparatively mild and short-term infection.
Below is an overview of medical and other articles about post-acute long covid.
Even after “normal” pneumonia, complete regeneration often takes one to three months. Moreover, symptoms such as fatigue and coughing are always prevalent in the general population, which is why a control group is important for any serious study on long covid.
- Management of post-acute covid-19 in primary care (British Medical Journal, August 2020)
- Long term respiratory complications of covid-19 (British Medical Journal, August 2020)
- Covid-19: Impact of long term symptoms will be profound (BMJ, August 2020)
- US CDC study on Covid-19 symptom duration among outpatients (CDC, July 2020)
- Three quarters of patients report long-term effects of coronavius (Bristol Univ., 08/20)
- Researchers Investigate What COVID-19 Does to the Heart (JAMA, February 2021)
- COVID-19 patients suffer long-term lung and heart damage (EurekAlert, Sept. 2020)
- New Insights into How COVID-19 Causes Heart Damage (Biospace, August 2020)
- Cardiac Infection in Confirmed COVID-19 Autopsy Cases (JAMA-C, August 2020)
- Cardiac Involvement in Patients Recovered From COVID-2019 (JACC, May 2020)
- One in 20 people likely to suffer from “long covid” (Covid Symptome Study, Oct. 2020)
- The lasting misery of coronavirus long-haulers (Nature, September 2020)
- Long covid case studies and expert opinions (Business Insider, September 2020)
- Three Months In, These Patients Are Still Ravaged By Covid’s Fallout (WSJ, July 2020)
- COVID-19 Can Last for Several Months (The Atlantic, June 2020)