Safety and Immunogenicity Study of an Inactivated SARS-CoV-2 Vaccine for Preventing Against COVID-19

This phase Ia/IIa trial is designed to evaluate the safety and immunogenicity of different doses of the Inactivated SARS-CoV-2 Vaccine inoculated with different immunization schedules based upon the randomized, double-blind and placebo-controlled principle. A total of 942 subjects aged 18 to 59 years old will be enrolled in the study, of which 192 and 750 will be enrolled for phase Ia and phase Ⅱa,respectively.The enrolled subjects in phase Ia receive two doses of low-, medium-, or high-dose of experimental vaccines or placebo at an interval of 14 or 28 days, while the enrolled subjects in Phase Ⅱa receive two doses of medium, high-dose experimental vaccines or placebo at an interval of 14 or 28 days.