inclusion criteria: - 18 years or older - covid-19 infection with severe disease defined within the last 12 months (defined as one or more of the following: hospitalization, need for oxygen supply, need for intensive care treatment, need for specific treatment of covid disease, antibiotic treatment) - subjective presence of residual symptoms of covid disease or no residual symptoms of covid disease (controls) - informed consent

inclusion criteria: - 18 years or older - covid-19 infection with severe disease defined within the last 12 months (defined as one or more of the following: hospitalization, need for oxygen supply, need for intensive care treatment, need for specific treatment of covid disease, antibiotic treatment) - subjective presence of residual symptoms of covid disease or no residual symptoms of covid disease (controls) - informed consent