1. The patient signed an informed consent form to participate in the study of convalescent plasma therapy, 2.The age of the patient is 18 or more than18 years old, 3. COVID-19 patients diagnosed by PCR, 4. Nucleic acid positive within 72 hours before blood transfusion, 5. Pneumonia confirmed by imaging, 6. The clinical symptoms reach the standard of severe or critical. Severe patients meet any of the following: a) respiratory distress, RR = 30 beats / min, b) in resting state, oxygen saturation = 93%, c) partial pressure of oxygen in arterial blood (PaO2) / oxygen concentration (FiO2) = 300mmHg (1mmHg=0.133kPa) Critically ill patients meet any of the following: a) respiratory failure and need mechanical ventilation, b) shock, c) patients with other organ failure need ICU monitoring treatment. 7. Accept random grouping into any group, 8. The patient was hospitalized before the end of the clinical study. 9. Willing to participate in all necessary research directions and be able to participate in follow-up, 10. During the period of participating in this study, they will no longer participate in clinical trials such as other antiviral drugs.

1. The patient signed an informed consent form to participate in the study of convalescent plasma therapy, 2.The age of the patient is 18 or more than18 years old, 3. COVID-19 patients diagnosed by PCR, 4. Nucleic acid positive within 72 hours before blood transfusion, 5. Pneumonia confirmed by imaging, 6. The clinical symptoms reach the standard of severe or critical. Severe patients meet any of the following: a) respiratory distress, RR = 30 beats / min, b) in resting state, oxygen saturation = 93%, c) partial pressure of oxygen in arterial blood (PaO2) / oxygen concentration (FiO2) = 300mmHg (1mmHg=0.133kPa) Critically ill patients meet any of the following: a) respiratory failure and need mechanical ventilation, b) shock, c) patients with other organ failure need ICU monitoring treatment. 7. Accept random grouping into any group, 8. The patient was hospitalized before the end of the clinical study. 9. Willing to participate in all necessary research directions and be able to participate in follow-up, 10. During the period of participating in this study, they will no longer participate in clinical trials such as other antiviral drugs.