1. Admitted to a hospital with a diagnosis of critical type of COVID-19 pneumonia defined as any of the follow: i) requiring mechanical ventilation, ii) extracorporeal life support (ECMO, ECCO2R, RRT), iii) shock, iv) multiple organ dysfunction syndrome. Patients who are participating in another drug clinical trials. 2. Requiring dialysis. 3. Pregnancy or breast feeding. 4. Allergy to any study medication. 5. Severe basic diseases that affect survival, including uncontrolled malignant tumors that have metastasized and cannot be removed, blood diseases, cachexia, active bleeding, severe malnutrition, HIV, etc., 6. Pulmonary tumors caused by obstructive pneumonia, severe interstitial fibrosis, alveolar proteinosis, allergic alveolitis. 7. Continued use of immunosuppressive agents or organ transplants in the last 6 months. 8. Expected deaths within 48 hours. 9. Clinicians judge inappropriate.

1. Admitted to a hospital with a diagnosis of critical type of COVID-19 pneumonia defined as any of the follow: i) requiring mechanical ventilation, ii) extracorporeal life support (ECMO, ECCO2R, RRT), iii) shock, iv) multiple organ dysfunction syndrome. Patients who are participating in another drug clinical trials. 2. Requiring dialysis. 3. Pregnancy or breast feeding. 4. Allergy to any study medication. 5. Severe basic diseases that affect survival, including uncontrolled malignant tumors that have metastasized and cannot be removed, blood diseases, cachexia, active bleeding, severe malnutrition, HIV, etc., 6. Pulmonary tumors caused by obstructive pneumonia, severe interstitial fibrosis, alveolar proteinosis, allergic alveolitis. 7. Continued use of immunosuppressive agents or organ transplants in the last 6 months. 8. Expected deaths within 48 hours. 9. Clinicians judge inappropriate.