Inclusion Criteria:
* SARS-CoV-2 infection confirmed by positive PCR or rapid antigen test for professional use or written medical report
* Post-COVID condition (WHO definition), i.e., ≥ 3 months after SARS-CoV2 infection and ongoing or recurring symptoms for at least 2 months that cannot be explained by alternative diagnosis
* Symptoms include fatigue and / or cognitive impairment ("brain fog") and / or dyspnea and / or post-exertional malaise
* Willing to participate and having signed informed consent
* Sufficient language and cognitive skills
* Ability to participate in study visits
* No foreseeable change in medication
Exclusion Criteria:
* Severe comorbidities such as liver or renal failure, advanced COPD or pulmonary fibrosis requiring \> 5L oxygen/min at rest, active malignancy, advanced heart failure, cardio-vascular events within the previous 24 weeks (such as unstable coronary artery disease, coronary revascularization, myocardial infarction, stroke, transient ischemic attack, critical limb ischemia, pulmonary embolism, deep vein thrombosis), uncontrolled severe hypertension, uncontrolled diabetes uncontrolled autoimmune or inflammatory disease (the responsible study physician will decide each case on an individual basis)
* Acute respiratory or other infections (postpone baseline visit until resolved)
* Clinical diagnosis of a psychiatric disease (e.g., depression, anxiety disorder, schizophrenia) that is untreated and/or unstable (the responsible study physician will decide each case on an individual basis)
* COVID-19 vaccination less than 4 weeks prior to the baseline visit (i.e., first or second dose of a two-dose vaccination regimen, first dose of a single dose vaccination regimen, booster) or during study participation (booster shot will be offered at screening visit, wait time until baseline visit 4 weeks)
* Known intolerance of the study drug
* Regular intake of Pycnogenol®
* Pregnancy or lactating. For women and transgender individuals of childbearing age, who can anamnestically not exclude a pregnancy, are offered a pregnancy test during the study visits.
* Being enrolled in another interventional study that may interfere with the current study (the responsible study physician will decide each case on an individual basis)
