The food supplement Endocalyx is considered to support the endothelial glycocalyx integrity by supplying sulfated polysaccharides, anti-oxidant enzymes and additional substrates for glycocalyx synthesis. The investigators will study the effect of Endocalyx on endothelial, vascular and left ventricular myocardial function in patients with COVID-19 infection.

Sixty patients who have been hospitalized due to COVID-19 infection will be randomized to receive food supplement Endocalyx (4 capsules per day) (n=30) or placebo (n=30) for 4 consecutive months.

Inclusion Criteria:

• caucasian patients
• hospitalization for COVID-19 infection
• diagnosis of COVID-19 proven by PCR

Exclusion Criteria:

• Pregnancy and breastfeeding
• Foreseen inability to attend scheduled visits
• History of acute coronary syndrome. Coronary artery disease will be excluded by a clinical history, examination and electrocardiogram.
• Moderate or severe valve disease
• Primary cardiomyopathies
• Chronic obstructive pulmonary disease
• Asthma
• Chronic kidney disease (estimated glomerular filtration rate [eGFR] ≤60 ml/min/1.73 m2)
• Liver failure
• Malignancies