1. Critically severe COVID-19 acute respiratory distress syndrome (ARDS) cases requiring invasive mechanical ventilation at screening 2. Patients who have a severe concomitant illness that affects survival, including uncontrolled malignant tumor, blood dyscrasia, active bleeding, or patients with shock/or multiple organ failure at screening 3. Hypersensitivity or contraindication to any of the drugs used in the study 4. Patients with liver disease or cirrhosis (Child-Pugh >9 for ravidasvir and ?12 for daclatasvir) or abnormal liver enzyme tests above three times the upper limit values (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) 5. Cardiac ischemia with history of recurrent angina, clinically symptomatic cardiac abnormalities, or requirement for cardiac pacemaker 6. History of any malignancy within the last 5 years 7. History of solid organ or bone marrow transplantation 8. Patients who received treatment with any other investigational drug/device or involved in another clinical trial within 6 months prior to Screening 9. People living with HIV 10. Pregnant or breastfeeding subjects 11. Patients unable to comply with the procedures described in the protocol 12. Mentally or neurologically disabled patients not able to consent to their participation in the study

1. Critically severe COVID-19 acute respiratory distress syndrome (ARDS) cases requiring invasive mechanical ventilation at screening 2. Patients who have a severe concomitant illness that affects survival, including uncontrolled malignant tumor, blood dyscrasia, active bleeding, or patients with shock/or multiple organ failure at screening 3. Hypersensitivity or contraindication to any of the drugs used in the study 4. Patients with liver disease or cirrhosis (Child-Pugh >9 for ravidasvir and ?12 for daclatasvir) or abnormal liver enzyme tests above three times the upper limit values (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) 5. Cardiac ischemia with history of recurrent angina, clinically symptomatic cardiac abnormalities, or requirement for cardiac pacemaker 6. History of any malignancy within the last 5 years 7. History of solid organ or bone marrow transplantation 8. Patients who received treatment with any other investigational drug/device or involved in another clinical trial within 6 months prior to Screening 9. People living with HIV 10. Pregnant or breastfeeding subjects 11. Patients unable to comply with the procedures described in the protocol 12. Mentally or neurologically disabled patients not able to consent to their participation in the study