1. Patients who are clinically classified as severe and meet any of the following: 1) Shortness of breath, RR >=30 times / minute, 2) In the resting state, the oxygen saturation <=93%, 3) Arterial blood oxygen partial pressure (PaO2) / oxygen concentration (FiO2) <=300mmHg (1mmHg = 0.133kPa). At high altitudes (above 1000 meters), PaO2 / FiO2 is corrected according to the following formula: PaO2 / FiO2 x [Atmospheric Pressure (mmHg) / 760], Chest CT-scan showed that the lesions progressed significantly within 24 to 48 hours, 2. Have a significant disease other than SARS-CoV-2 infection, that is, a disease that, according to the investigator's judgment, may cause the subject to be at risk because of participation in the research, or have an impact on the results of the research and the ability of the subject to participate in the research, 3. A history of severe heart disease such as acute myocardial infarction, congestive heart failure (NYHA Class III and above), severe arrhythmia, and other patients with acute heart disease, 4. There are serious primary diseases of important organs and systems: such as acute stroke, moderate or higher hypertension after treatment, active gastric ulcer, diabetes (serious complications), malignant tumor, etc ., 5. Limited understanding and poor compliance, 6. Does not have legal capacity or is restricted, 7. Pregnant, lactating women and women of childbearing age who do not agree to effective contraception during the study, 8. Researchers do not consider it appropriate to participate in this research.

1. Patients who are clinically classified as severe and meet any of the following: 1) Shortness of breath, RR >=30 times / minute, 2) In the resting state, the oxygen saturation <=93%, 3) Arterial blood oxygen partial pressure (PaO2) / oxygen concentration (FiO2) <=300mmHg (1mmHg = 0.133kPa). At high altitudes (above 1000 meters), PaO2 / FiO2 is corrected according to the following formula: PaO2 / FiO2 x [Atmospheric Pressure (mmHg) / 760], Chest CT-scan showed that the lesions progressed significantly within 24 to 48 hours, 2. Have a significant disease other than SARS-CoV-2 infection, that is, a disease that, according to the investigator's judgment, may cause the subject to be at risk because of participation in the research, or have an impact on the results of the research and the ability of the subject to participate in the research, 3. A history of severe heart disease such as acute myocardial infarction, congestive heart failure (NYHA Class III and above), severe arrhythmia, and other patients with acute heart disease, 4. There are serious primary diseases of important organs and systems: such as acute stroke, moderate or higher hypertension after treatment, active gastric ulcer, diabetes (serious complications), malignant tumor, etc ., 5. Limited understanding and poor compliance, 6. Does not have legal capacity or is restricted, 7. Pregnant, lactating women and women of childbearing age who do not agree to effective contraception during the study, 8. Researchers do not consider it appropriate to participate in this research.