An Open Non-comparative Study of the Efficacy and Safety of Aprotinin in Patients Hospitalized With COVID-19

Inclusion Criteria: 1. Signed Patient Information Sheet and Informed Consent Form for participation in the study; 2. Adult male or female ≥18 years of age; 3. Body mass \< 90 kg; 4. Positive qualitative RNA SARS-CoV-2 PCR analysis at screening; 5. Score 4 on the WHO-OSCI (added at Stage 2); 6. Subjects with moderate-to-severe disease with the follow conditions and symptoms: * Pneumonia; * Fever \> 38°C; * Blood serum CRP \> 10 mg/L. 7. Agreement to use medically acceptable forms of birth control during the study (contraceptive with spermicide). Exclusion Criteria: 1. Severe disease with one of the follow criteria: * Respiratory rate \> 35 per minute that doesn't decrease after body temperature reducing to normal or subfebrile level; * Saturation ≤ 93% at rest; * Partial pressure of arterial oxygen (PaO2) \< 60 mmHg; * Oxygenation index (РаО2/FiO2) ≤ 200 mmHg; * Partial pressure of arterial CO2 (PaCO2) \> 60 mmHg; * Septic shock. 2. Chronic liver and kidney diseases in terminal stage; 3. Other organs failure requiring control and treatment in the ICU; 4. Subjects with HIV; 5. Using of Aprotinin during 6 months prior to screening; hypersensitivity to any of the drug components; 6. Participation in any other clinical trial or using of other study drugs during 28 days prior to screening; 7. Pregnant or lactating women or women planning pregnancy during the clinical study; women with child-bearing potential (including women non-sterilized surgically and in postmenopause for less than 2 years) not using medically acceptable forms of birth control; 8. Inability to read or write; unwillingness to understand and follow the Protocol procedures; non-compliance with the regimen of taking medications or performing procedures that, according to the Investigator, may affect the results of the study or the safety of the patient and prevent the patient from further participation in the study; any other comorbid medical or serious mental conditions that make patient ineligible for participation in the clinical study, limits the ability to obtain informed consent, or may affect patient's ability to participate in the study.