Inclusion Criteria:  Age between 18 and 75 years Male or female SARS-CoV-2 infection indicated by confirmed RT-PCR test  Moderate hospitalized COVID-19 (at least two out of three criterias below):  Evidence of lower respiratory disease during clinical assessment (cough, fever, difficulty breathing) or imaging (X-rays) Oxygen saturation (SpO2) in room air < 93% <30 breaths per minute No signs of hemodynamic decompensation Absence of pregnancy in women of childbearing age Ability to understand and comply with the requirements of the protocol Consent to participate Consent to use at least one highly effective contraception methods (condoms, IUD, oral contraceptives) since the ICF signature and at least 30 days after the study.  Exclusion Criteria:  Patients receiving oxygen supplementation except of nasal prongs, nasal intermittent positive pressure ventilation (NIPPV) or high flow nasal cannula (HFNC) that are allowed to be enrolled to the study). Positive RT-PCR test more than 72 hours prior to enrolment. Onset of symptoms more than 7 days prior to enrolment. Participant using drugs that are under clinical investigation in last 30 days. Body mass index less than 19.9 or greater than 35. Comorbidities such as: other serious infections, active malignancies, autoimmune diseases, liver, kidney or heart failure; another systemic disease and / or laboratory abnormality, which, in the investigator's opinion, prevent the patient from participating in the study. Concomitant HIV, HBV or HCV infection. Pregnancy or lactation. Vaccination for any other infection in the 4 weeks prior to enrolment. Any condition that increases the risk of participating in the study, in the opinion of the investigator.