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).
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), neurological (nerves), pulmonary (lungs) 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 affected persons, including young people from around 30 years of age, report significant restrictions in their everyday life, such as exhaustion after climbing stairs, as well as psychological effects. Persistent infectiousness seems unlikely, but cannot be completely excluded at present.
Initial studies found involvement of the heart muscle (myocarditis) in a considerable proportion of mild and moderate Covid cases (without hospitalization). It is also known that even in apparently asymptomatic covid disease, some limited lung inflammation can occur in about 50% of cases. People with persistent chest pain or other persistent or new symptoms are therefore advised to consult a doctor for an assessment.
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 “long covid” is therefore not entirely surprising, but it is nevertheless remarkably widespread and must be taken seriously.
Many people affected by long covid report a slow, wave-like improvement in 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 “long covid”.