Effect of COVID-19 on Endothelial Function

COVID-19 disease (coronavirus disease 2019) primarily affects the respiratory system, using the angiotensin-converting enzyme 2 receptor. However, there is increasing evidence that COVID-19 can also affect the heart (myocardial injury, myocarditis, arrhythmias) and the vascular system, effects that may worsen the clinical outcome of patients. The aim of this study is to assess the effect of COVID-19 on the patients' endothelial function, during the acute phase of the disease (inpatient), shortly after recovery (2 months) and in the mid-term (6 months). Evaluation of endothelial function will be performed non-invasively by the method of Peripheral Arterial Tonometry (PAT) using the EndoPAT2000 system (Itamar Medical, Israel). This is a prospective, case-controlled, single-center clinical observational study. The study will include adult patients who developed COVID-19 disease for whom admission for hospitalization was required, while the control group will consist of healthy volunteers matched for age, gender and cardiovascular risk factors. Patients enrolled in the study will undergo the following visits: * Visit 1: Hospitalization * Visit 2: 2 months after discharge * Visit 3: 6 months after discharge * Visit 4: 1 year after discharge Patients will be subjected to measurement of the reactive hyperemia index with the EndoPAT2000 system in Visits 1, 2 and 3. The aim of the study is to compare the endothelial function between the two groups (COVID-19 vs. Controls).