1. a subject who was diagnosed with severe or critical covid-19 (as per the diagnosis and treatment protocol for novel coronavirus pneumonia (trial, 8th edition), china, or clinical management of covid-19, who); 2. abnormal important organ function indicators, which meet the following conditions: ① liver function: serum aspartate aminotransferase (ast) and serum alanine aminotransferase (alt) \> 5.0 × upper limit of normal (uln); ② renal function: patients treated with dialysis or egfr\< 60 ml/min. ③ cardiac function: patients with results of 12-lead ecg suggesting conduction block or acute myocardial infarction requiring urgent management; 3. suspected or diagnosed with serious bacterial, fungal, viral, or other infection (except sars-cov-2 infection). in the opinion of the investigator, the conditions will prevent a subject from completing the study or impact interpretation of the study results; 4. currently suffering from serious systemic diseases or mental disorders, and ineligible to participate in the study judged by the investigator; 5. a history of severe trauma, fracture, or surgery within 4 weeks prior to screening, or possibility of requiring a major surgery during the study; 6. participated in clinical trials of sars-cov-2 vaccine or sars-cov-2 monoclonal antibody; 7. received or being receiving the convalescent plasma from patients recovered from covid-19; 8. prior or current use of antiviral drugs for treatment of covid-19, including remdesivir, tocilizumab, interferon, ribavirin, abidol, lopinavir, and ritonavir, etc. 9. currently enrolled into clinical studies with other drugs or devices; the time to start of this study from the end of previous participation in other drug clinical studies is less than 30 days, or within 5 half-lives, or within the biological effect period of the drug (whichever is longer); 10. those who are known to be allergic to any component of the investigational product; or those who have a history of allergies and judged by the investigator to be ineligible for enrollment; 11. females who are pregnant or lactating; 12. any conditions that are not suitable for enrollment judged by the investigator.

1. a subject who was diagnosed with severe or critical covid-19 (as per the diagnosis and treatment protocol for novel coronavirus pneumonia (trial, 8th edition), china, or clinical management of covid-19, who); 2. abnormal important organ function indicators, which meet the following conditions: ① liver function: serum aspartate aminotransferase (ast) and serum alanine aminotransferase (alt) \> 5.0 × upper limit of normal (uln); ② renal function: patients treated with dialysis or egfr\< 60 ml/min. ③ cardiac function: patients with results of 12-lead ecg suggesting conduction block or acute myocardial infarction requiring urgent management; 3. suspected or diagnosed with serious bacterial, fungal, viral, or other infection (except sars-cov-2 infection). in the opinion of the investigator, the conditions will prevent a subject from completing the study or impact interpretation of the study results; 4. currently suffering from serious systemic diseases or mental disorders, and ineligible to participate in the study judged by the investigator; 5. a history of severe trauma, fracture, or surgery within 4 weeks prior to screening, or possibility of requiring a major surgery during the study; 6. participated in clinical trials of sars-cov-2 vaccine or sars-cov-2 monoclonal antibody; 7. received or being receiving the convalescent plasma from patients recovered from covid-19; 8. prior or current use of antiviral drugs for treatment of covid-19, including remdesivir, tocilizumab, interferon, ribavirin, abidol, lopinavir, and ritonavir, etc. 9. currently enrolled into clinical studies with other drugs or devices; the time to start of this study from the end of previous participation in other drug clinical studies is less than 30 days, or within 5 half-lives, or within the biological effect period of the drug (whichever is longer); 10. those who are known to be allergic to any component of the investigational product; or those who have a history of allergies and judged by the investigator to be ineligible for enrollment; 11. females who are pregnant or lactating; 12. any conditions that are not suitable for enrollment judged by the investigator.

a subject who was diagnosed with severe or critical covid-19 (as per the diagnosis and treatment protocol for novel coronavirus pneumonia (trial, 8th edition), china, or clinical management of covid-19, who); abnormal important organ function indicators, which meet the following conditions: ① liver function: serum aspartate aminotransferase (ast) and serum alanine aminotransferase (alt) > 5.0 × upper limit of normal (uln); ② renal function: patients treated with dialysis or egfr< 60 ml/min. ③ cardiac function: patients with results of 12-lead ecg suggesting conduction block or acute myocardial infarction requiring urgent management; suspected or diagnosed with serious bacterial, fungal, viral, or other infection (except sars-cov-2 infection). in the opinion of the investigator, the conditions will prevent a subject from completing the study or impact interpretation of the study results; currently suffering from serious systemic diseases or mental disorders, and ineligible to participate in the study judged by the investigator; a history of severe trauma, fracture, or surgery within 4 weeks prior to screening, or possibility of requiring a major surgery during the study; participated in clinical trials of sars-cov-2 vaccine or sars-cov-2 monoclonal antibody; received or being receiving the convalescent plasma from patients recovered from covid-19; prior or current use of antiviral drugs for treatment of covid-19, including remdesivir, tocilizumab, interferon, ribavirin, abidol, lopinavir, and ritonavir, etc. currently enrolled into clinical studies with other drugs or devices; the time to start of this study from the end of previous participation in other drug clinical studies is less than 30 days, or within 5 half-lives, or within the biological effect period of the drug (whichever is longer); those who are known to be allergic to any component of the investigational product; or those who have a history of allergies and judged by the investigator to be ineligible for enrollment; females who are pregnant or lactating; any conditions that are not suitable for enrollment judged by the investigator.

a subject who was diagnosed with severe or critical covid-19 (as per the diagnosis and treatment protocol for novel coronavirus pneumonia (trial, 8th edition), china, or clinical management of covid-19, who); abnormal important organ function indicators, which meet the following conditions: ① liver function: serum aspartate aminotransferase (ast) and serum alanine aminotransferase (alt) > 5.0 × upper limit of normal (uln); ② renal function: patients treated with dialysis or egfr< 60 ml/min. ③ cardiac function: patients with results of 12-lead ecg suggesting conduction block or acute myocardial infarction requiring urgent management; suspected or diagnosed with serious bacterial, fungal, viral, or other infection (except sars-cov-2 infection). in the opinion of the investigator, the conditions will prevent a subject from completing the study or impact interpretation of the study results; currently suffering from serious systemic diseases or mental disorders, and ineligible to participate in the study judged by the investigator; a history of severe trauma, fracture, or surgery within 4 weeks prior to screening, or possibility of requiring a major surgery during the study; participated in clinical trials of sars-cov-2 vaccine or sars-cov-2 monoclonal antibody; received or being receiving the convalescent plasma from patients recovered from covid-19; prior or current use of antiviral drugs for treatment of covid-19, including remdesivir, tocilizumab, interferon, ribavirin, abidol, lopinavir, and ritonavir, etc. currently enrolled into clinical studies with other drugs or devices; the time to start of this study from the end of previous participation in other drug clinical studies is less than 30 days, or within 5 half-lives, or within the biological effect period of the drug (whichever is longer); those who are known to be allergic to any component of the investigational product; or those who have a history of allergies and judged by the investigator to be ineligible for enrollment; females who are pregnant or lactating; any conditions that are not suitable for enrollment judged by the investigator.

1. a subject who was diagnosed with severe or critical covid-19 (as per the diagnosis and treatment protocol for novel coronavirus pneumonia (trial, 8th edition), china, or clinical management of covid-19, who); 2. abnormal important organ function indicators, which meet the following conditions: ① liver function: serum aspartate aminotransferase (ast) and serum alanine aminotransferase (alt) > 5.0 × upper limit of normal (uln); ② renal function: patients treated with dialysis or egfr< 60 ml/min. ③ cardiac function: patients with results of 12-lead ecg suggesting conduction block or acute myocardial infarction requiring urgent management; 3. suspected or diagnosed with serious bacterial, fungal, viral, or other infection (except sars-cov-2 infection). in the opinion of the investigator, the conditions will prevent a subject from completing the study or impact interpretation of the study results; 4. currently suffering from serious systemic diseases or mental disorders, and ineligible to participate in the study judged by the investigator; 5. a history of severe trauma, fracture, or surgery within 4 weeks prior to screening, or possibility of requiring a major surgery during the study; 6. participated in clinical trials of sars-cov-2 vaccine or sars-cov-2 monoclonal antibody; 7. received or being receiving the convalescent plasma from patients recovered from covid-19; 8. prior or current use of antiviral drugs for treatment of covid-19, including remdesivir, tocilizumab, interferon, ribavirin, abidol, lopinavir, and ritonavir, etc. 9. currently enrolled into clinical studies with other drugs or devices; the time to start of this study from the end of previous participation in other drug clinical studies is less than 30 days, or within 5 half-lives, or within the biological effect period of the drug (whichever is longer); 10. those who are known to be allergic to any component of the investigational product; or those who have a history of allergies and judged by the investigator to be ineligible for enrollment; 11. females who are pregnant or lactating; 12. any conditions that are not suitable for enrollment judged by the investigator.

1. a subject who was diagnosed with severe or critical covid-19 (as per the diagnosis and treatment protocol for novel coronavirus pneumonia (trial, 8th edition), china, or clinical management of covid-19, who); 2. abnormal important organ function indicators, which meet the following conditions: ① liver function: serum aspartate aminotransferase (ast) and serum alanine aminotransferase (alt) > 5.0 × upper limit of normal (uln); ② renal function: patients treated with dialysis or egfr< 60 ml/min. ③ cardiac function: patients with results of 12-lead ecg suggesting conduction block or acute myocardial infarction requiring urgent management; 3. suspected or diagnosed with serious bacterial, fungal, viral, or other infection (except sars-cov-2 infection). in the opinion of the investigator, the conditions will prevent a subject from completing the study or impact interpretation of the study results; 4. currently suffering from serious systemic diseases or mental disorders, and ineligible to participate in the study judged by the investigator; 5. a history of severe trauma, fracture, or surgery within 4 weeks prior to screening, or possibility of requiring a major surgery during the study; 6. participated in clinical trials of sars-cov-2 vaccine or sars-cov-2 monoclonal antibody; 7. received or being receiving the convalescent plasma from patients recovered from covid-19; 8. prior or current use of antiviral drugs for treatment of covid-19, including remdesivir, tocilizumab, interferon, ribavirin, abidol, lopinavir, and ritonavir, etc. 9. currently enrolled into clinical studies with other drugs or devices; the time to start of this study from the end of previous participation in other drug clinical studies is less than 30 days, or within 5 half-lives, or within the biological effect period of the drug (whichever is longer); 10. those who are known to be allergic to any component of the investigational product; or those who have a history of allergies and judged by the investigator to be ineligible for enrollment; 11. females who are pregnant or lactating; 12. any conditions that are not suitable for enrollment judged by the investigator.