Study to Investigate Improvement in Physical Function in SF-36 With Vericiguat Compared With Placebo in Participants With Post-COVID-19 Syndrome

Inclusion Criteria: * Male or female adult who is 18-50 years old * Confirmed (PCR or serology), non-hospitalized, mild to moderate acute COVID-19 cases according to WHO criteria with proven chronic ED and either: ME/CFS Canadian Consensus Criteria (CCC) with post exertional malaise (PEM) 2 - 14 hours = PCS or ME/CFS CCC criteria with PEM \> 14 hours = PCS/CFS * Ongoing symptoms of PCS or PCS/CFS for ≥ 6 months * Bell Score: 30-60 * Evidence for endothelial dysfunction (ED) \[as indicated by reactive hyperemia index (RHI) \< 1.8 and/or ET-1 level \> 90 percentile of healthy age- and gender matched controls or muscle fatigue (below cut-off values of area under the curve reference values for age-matched healthy controls and/or pathological optical coherence tomography angiography (OCTA))\] * For female subjects: Confirmed post-menopausal state (defined as amenorrhea for at least 12 months) or for women of childbearing potential: Negative highly sensitive urine or serum pregnancy test before inclusion/randomisation and practicing a highly effective birth control method (failure rate of less than 1 %): * combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral/intravaginal/transdermal), or * progestogen-only hormonal contraception associated with inhibition of ovulation (oral/injectable/implantable), or * intrauterine device, or * intrauterine hormone-releasing system, or * bilateral tubal occlusion, or * vasectomised partner, or * heterosexual abstinence. Exclusion Criteria: * COVID-19 vaccination within the last 4 weeks before inclusion * Pre-COVID history of chronic fatigue syndrome or other fatigue syndromes that are due to associated diseases (e.g., cancer, autoimmune diseases \[patients with a preexisting Hashimoto thyroiditis and/or fibromyalgia without fatigue syndromes can be included\]) * Concomitant use of Vericiguat due to other diseases * Contraindications against IMP * Concurrent or anticipated concomitant use of PDE-5 inhibitors such as vardenafil, tadalafil, and sildenafil, nitrates, or sGC-stimulators * Use of other sGC stimulators, e.g., riociguat * Hypersensitivity to the active substance or any of the other ingredients * Systolic blood pressure: \< 100 mmHg at screening * Known SARS-CoV-2 infection-related organ damage/comorbidity * Severe renal or hepatic insufficiency * Pregnancy or breastfeeding