In this study, Phase II part will evaluate the efficacy, safety and PK of SCTA01 low dose+BSC, high dose+BSC and placebo+BSC in patients with severe COVID-19.
In Phase II part, subjects will be randomized at 1:1:1 ratio. At the end of Phase II part, a dose for the Phase III will be determined.
The Phase III part will evaluate the efficacy, safety, and immunogenicity of SCTA01 at the recommended dose recommended. Subjects in Phase III part will be randomized at 1:1 ratio to SCTA01+BSC and placebo+BSC groups.
