Approximately 1,800 participants aged 18 years old and above will be enrolled in this study. 1,350 participants who previously received Sinopharm inactivated COVID-19 vaccine will be enrolled to Cohort 1. 450 participants who previously received mRNA COVID-19 vaccine or previously diagnosed with COVID-19 will be enrolled to Cohort 2.
The study is a randomized, double-blind, and positive-controlled Phase III booster study. It will evaluate the immunogenicity and safety of one dose of SCTV01C or SCTV01E as booster compared with either one dose of Sinopharm inactivated COVID-19 vaccine (Cohort 1) or one dose of Comirnaty (Cohort 2).