Due to the lack of funding from the sponsor, the research drug and placebo cannot be obtained.

The primary objective of this study is to evaluate the effectiveness of tetrandrine tablets in preventing the progression of COVID-19 from severe to critical.

The primary objective of this study is to evaluate the effectiveness of tetrandrine tablets in preventing the progression of COVID-19 from severe to critical. The secondary objective is to evaluate the clinical indicators of COVID-19 with tetrandrine tablets treatment.

Inclusion Criteria:

1. Sign informed consent form voluntarily for the trial.
2. Male or female aged between 18 and 85 years (inclusive).
3. Clinically or laboratory confirmed COVID-19 within the past 7 days, as determined by a positive RT-PCR test or a positive antigen test.
4. Under resting conditions, oxygen saturation ≤93% when breathing air, or P/F value ≤ 300 mmHg (1 mmHg = 0.133 kPa).
5. No birth plan and must agree to take effective contraceptive methods.

Exclusion Criteria:

1. Received a vaccine within 4 weeks prior to the study, or plan to receive a vaccine during the study period, or received treatment with tetrandrine tables prior to enrolling in the study.
2. Patient must be on invasive mechanical ventilation/ECMO at baseline.
3. Any clinically important serious diseases unstable or uncontrolled.
4. Allergy history to any biological or other agent.
5. Patient has severe mental or psychological abnormalities, cognitive impairment or intellectual disability before being diagnosed with COVID-19.
6. Subjects who are pregnant or breastfeeding, or plan to become pregnant during the study.
7. Investigator think the subject should not participate in the study.