Post Covid Syndrome (“Long Covid”)

Updated: August 2021
Published: August 2020
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Post covid syndrome: Frequency, causes and treatment options.

Contents: A) Frequency; B) Symptoms; C) Causes; D) Diagnosis; E) Treatment; F) Prevention; G) Children; H) Post-viral syndrome; J) Myocarditis; K) Media reporting

Note: Patients are asked to consult a doctor.

A. Frequency

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).

According to a British ONS survey published in April 2021, 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 published in Nature Medicine and based on somewhat different criteria, only 2% had symptoms lasting longer than three months.

B. Symptoms

Frequently reported symptoms include persistent coughing, moderate fever, general fatigue or exhaustion, shortness of breath, chest pain, hoarseness, heart palpitations, headaches, concentration problems, muscle pain, digestive problems, skin rashes and metabolic symptoms.

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 may be covid-induced pneumonia.

C. Causes of post-acute symptoms

The exact cause of persistent post-acute covid symptoms is not yet clear, but there is increasing evidence that pulmonary endothelial dysfunction and possibly pulmonary micro-thrombosis may play a crucial role in major symptoms of post-acute covid, including chest pain, shortness of breath, fatigue, exercise intolerance, dizziness and tachycardia (heart racing).

Studies have shown that Sars-CoV-2, which uses the ACE2 cell receptor present on endothelial cells, may cause endotheliitis (inflammation of blood vessels) and micro-thrombosis (micro blood clots), which in turn might give rise to pulmonary and cardiovascular post-covid symptoms.

Severe cases of post-acute covid syndrome have been compared to POTS (Postural Orthostatic Tachycardia Syndrom). In April 2021, a US study for the first time could independently show that POTS is itself caused by or linked to endothelial dysfunction.

Other potential causes of post-acute covid symptoms might include neurological, cardiac, metabolic and immunological conditions (including auto-immune reactions). However, additional studies will be required to clarify their potential role.

D. Diagnosis

Pulmonary endothelial dysfunction may not be visible in standard x-ray and CT scans, nor in CT angiography scans and standard lung function tests, but may be visible in specialized gas-exchange tests and in lung ventilation/perfusion gamma scans (see annex below).

Sars-CoV-2 antibodies may or may not be measurable at the time of diagnosis, depending on the severity of the acute disease, the time since the acute disease, the age and sex of the patient, and the sensitivity of the antibody test assay.

E. Treatment options

Note: Patients are asked to consult a doctor.

Currently, several ongoing trials focusing on post-covid symptoms related to endothelial dysfunction or micro-thrombosis apply anticoagulation therapy, using drugs such as apixaban or sulodexide.

  1. UK HEAL-COVID trial on the treatment of long Covid (NHS, March 2021)
  2. A diagnosis for Long Covid (Jasmine Hayer, Medium, March 2021)
  3. Endothelial Dysfunction during the COVID-19 follow-up (ENDCOV, Feb. 2021)
  4. Discussion of TUN-ENDCOV medical study (ENDCOV, April 2021)
  5. Sulodexide in the early stages of COVID-19 (Ochoa et al., April 2021)

See also: The FLCCC I-RECOVER Protocol

F. Preventing post-acute covid

To avoid the risk of 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. If covid symptoms nevertheless persist or return, post-covid tests and treatment options should be considered.

It has been argued that vaccination may prevent “long covid” or multi-system inflammatory syndrome (MIS) in children and young adults; however, recent reports indicate that covid vaccines may themselves cause MIS and “long covid”-like conditions. Moreover, vaccination cannot prevent infection (only severe disease), and long covid has been reported even in vaccinated people.

G. Post-acute covid in children

According to an Australian study published in The Lancet, post-acute covid symptoms in children are rather rare (8%), generally mild (mild cough or fatigue), and mostly of short duration (3 to 8 weeks). About one third of children remained completely asymptomatic. A larger British study found that among 1,400 PCR-positive children, 1.8% experienced symptoms for more than 56 days.

Nevertheless, case reports of persistent post-covid symptoms in children, especially in previously hospitalized children, do exist.

H. Comparison to post-viral syndrome

The so-called post-viral syndrome or post-viral fatigue is already known from other viral infections, including severe influenza. The occurrence of post-acute covid is therefore not entirely surprising or unusual, but it is nevertheless quite widespread and must be taken seriously.

J. The role of myocarditis

Initial studies reported inflammation of the heart muscle (myocarditis) in a very high proportion of mild and moderate covid cases. However, later studies could not confirm this finding, instead reporting generally mild myocarditis with a frequency 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.” Nevertheless, in case of post-covid cardiac symptoms, patients should immediately consult a doctor.

See also: Setting the record straight: There is no ‘Covid heart’ (StatNews, May 2021)

K. Quality of research and media reporting

Many studies on post-acute covid are of poor quality. For instance, many studies include people without PCR or antibody confirmation; refer to non-representative patient cohorts; apply unsuitable diagnostic criteria; do not include a control group; or do not apply a symptom severity score. In addition, many media reports further exaggerate low-quality research on post-acute covid.

Thus, the public perception of long covid is likely to be distorted. Nevertheless, high-quality research and clinical experience show that true long covid is a real and significant health issue.


A. Perfusion and gas exchange in the lungs

Lung perfusion gamma scan in a young long covid patient one year after “mild” covid, showing significantly reduced perfusion in the upper right lung.

Reduced lung perfusion in a young woman one year after “mild” covid (Source)
B. Symptom duration

According to the British ONS, about 14% of PCR-confirmed covid patients continue to report symptoms after three months, of which 20% report a “strong limitation” to their daily activities.

Symptom duration in people with covid vs. control group (Source: ONS)
C. Symptom duration after “normal” pneumonia

After “normal” pneumonia, complete regeneration may also take one to three months. Therefore, a post-covid diagnosis may require specialized tests (see above).

Duration and severity (0-100) of symptoms after “normal” pneumonia (Metlay 1997)


  1. The Hidden Voices of Long Covid (Jasmine Hayer, June 2021)
  2. Researchers Investigate What COVID-19 Does to the Heart (JAMA, February 2021)
  3. The lasting misery of coronavirus long-haulers (Nature, September 2020)
  4. Long term respiratory complications of covid-19 (British Medical Journal, August 2020)
  5. Covid-19: Impact of long term symptoms will be profound (BMJ, August 2020)
  6. Three Months In, These Patients Are Still Ravaged By Covid’s Fallout (WSJ, July 2020)
  7. COVID-19 Can Last for Several Months (The Atlantic, June 2020)

See also

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