Study of Favipiravir Compared to Standard of Care in Hospitalized Patients With COVID-19

Inclusion Criteria: 1. Signing and dating of the Informed Consent Form of the Patient Information Leaflet (PIL) by patients. 2. Men and women aged 18 to 80 years inclusive at the time of signing the Informed Consent Form in PIL. 3. No difficulty with oral medication (e.g. swallowing disorder). 4. Patient diagnosed with "Coronavirus infection caused by SARS-CoV-2 (confirmed)1, moderate severity form\*" established in accordance with the Interim Guidelines of the Russian Ministry of Health for the prevention, diagnosis and treatment of a new coronavirus infection (COVID-19), (revision 6 of 28.04.2020). \*Moderate severity form: fever above 38 °C, BR above 22/min, dyspnea during exercise, pneumonia (confirmed by lung CT), SpO2 \< 95%, C reactive protein (CRP) serum level above 10 mg/l. 5. Patient should be hospitalized no more than 48 hours before the start of the study therapy. 6. Positive PCR result for presence of SARS-CoV-2 RNA at screening phase (results obtained within 7 days prior to screening are appropriate). 7. Patient's consent to use reliable contraceptive methods throughout the study and within 1 month for women and 3 months for men after its completion. Persons eligible for participation in the study: - Women who have a negative pregnancy test and use the following contraceptives: barrier method (condom or occlusive cap (diaphragm or cervical/vaulted cap)) or double barrier method of contraception (condom or occlusive cap (diaphragm or cervical/vaulted cap) plus spermicide (foam/gel/film/cream/suppository)). Women incapable of childbearing may also participate in the study (with past history of: hysterectomy, tubal ligation, infertility, menopause more than 1 year) or men with preserved reproductive function who use barrier contraceptives, as well as men with infertility or vasectomy in the past medical history. Exclusion Criteria: 1. Hypersensitivity to favipiravir and/or other components of the study drug. 2. Impossibility of CT procedure (for example, gypsum dressing or metal structures in the field of imaging). 3. The need to use drugs from the list of prohibited therapy. 4. Need for treatment in the intensive care unit. 5. Impaired liver function (AST and/or ALT ≥ 2 UNL and/or total bilirubin ≥ 1.5 UNL) at the time of screening. 6. Impaired kidney function (creatinine clearance according to Cockcroft-Gault formula less than 45 ml/min) at the time of screening. 7. Positive testing for HIV, syphilis, hepatitis B and/or C. 8. Chronic heart failure FC III-IV according to New York Heart Association (NYHA) functional classification. 9. Malabsorption syndrome or other clinically significant gastrointestinal disease that may affect absorption of the study drug (non-correctable vomiting, diarrhea, ulcerative colitis, and others). 10. Malignancies in the past medical history. 11. Alcohol, pharmacological and/or drug addiction in the past medical history and/or at the time of screening. 12. Schizophrenia, schizoaffective disorder, bipolar disorder, or other history of mental pathology or suspicion of their presence at the time of screening. 13. Severe, decompensated or unstable somatic diseases (any disease or condition that threaten the patient's life or impair the patient's prognosis, and also make it impossible for him/her to participate in the clinical study). 14. Any history data that the investigating physician believes could lead to complication in the interpretation of the study results or create an additional risk to the patient as a result of his/her participation in the study. 15. Patient's unwillingness or inability to comply with procedures of the Study Protocol (in the opinion of physician investigator). 16. Pregnant or nursing women or women planning pregnancy. 17. Participation in another clinical study for 3 months prior to inclusion in the study. 18. Other conditions that, according to the physician investigator, prevent the patient from being included in the study.