Surfactant-BL in Adult Acute Respiratory Distress Syndrome Due to COVID-19

Inclusion Criteria: 1. Informed consent for participation in the study. 2. Male of female ≥18 and ≤ 75 years of age. 3. Body-mass index (BMI) ≤ 40 kg/m2. 4. Probable (the presence of a characteristic clinical findings of COVID-19 in combination with characteristic changes in the lungs according to computer tomography (CT) data) or confirmed (according to the results of laboratory tests for the presence of SARS-CoV-2 RNA using nucleic acid amplification methods) diagnosis of COVID-19. 5. ARDS diagnosed within 24 hours prior to screening and confirmed at screening according to the following criteria (adapted Berlin criteria): * bilateral darkening of the pulmonary fields (infiltration, pulmonary edema) on the chest CT, which cannot be fully explained by pleural effusion, lung tissue atelectasis, tumor or other neoplasms; * nature of pulmonary infiltrates: respiratory failure not associated with heart failure or fluid overload; * oxygenation index (РаО2/FiO2 ratio): 150 mm hg \< РаО2/FiO2 ≤ 300 mm hg at the positive end-expiratory pressure (PEEP) or the continuous positive air pressure (CPAP) ≥ 5 cm H2O. 6. Oxygen saturation of the blood according to pulseoximetry (SpO2) ≤ 93 % in ambient air. 7. No indications for immediate tracheal intubation and artificial lung ventilation (ALV). 8. Negative pregnancy test result (applicable to female patients with preserved breeding potential). Exclusion Criteria: 1. ARDS due to the other viral infections. 2. Non-pulmonary ARDS. 3. Comorbidities continuing at the time of the screening or a history of comorbidities that increase the risk of patient transfer to ALV or may be fatal within 3 months, including but not limited to the following: * Any autoimmune diseases. * Resistant hypertension. * A history of stable ischemic heart disease, chronic heart failure (NYHA class III / IV) or unstable angina. * Congenital / acquired QT interval prolongation and / or history of the risk factors for QT interval prolongation. * Tuberculosis. * Suspected active uncontrolled bacterial, fungal, viral, or other infections (other than COVID-19). * Chronic kidney disease stage 4 or the need for hemodialysis / peritoneal dialysis. * Multiple organ dysfunction syndrome. * Cancer. 4. Patients with HIV infection, viral hepatitis B and C. 5. History of organ transplantation. 6. History of conditions requiring ALV. 7. Idiosyncrasy of study drug components. 8. Pregnancy, lactation. 9. Participation in any interventional clinical trial of any drug product at the time of the screening.