This is a randomized, double blind, positive controlled study to evaluate the safety and immunogenicity of Omicron COVID-19 Vaccine (Vero Cell), Inactivated in population aged 18 years old and above who have been vaccinated with 2 or 3 doses of COVID-19 Vaccine (Vero Cell), Inactivated manufactured by Beijing Institute of Biological Products, Co., Ltd. According to subject's age (18-59 vs 60 and above), doses of vaccination history ( 2 doses vs 3 doses), and vaccination interval, the subjects will be stratified and assigned randomly to the study groups ( Omicron inactivated COVID-19 Vaccine) or the control groups ( Prototype inactivated COVID-19 Vaccine) in a 2:1 ratio. All subjects will receive single dose or two doses of vaccine with a interval of 28 days. The occurrence of adverse events within 28 days and serious adverse events within 12 months after vaccination will be observed. The serum antibody levels, cellular immune responses will be analyzed at different time points.
This is a randomized, double blind, positive controlled study to evaluate the safety and immunogenicity of Omicron COVID-19 Vaccine (Vero Cell), Inactivated in population aged 18 years old and above who have been vaccinated with 2 or 3 doses of COVID-19 Vaccine (Vero Cell), Inactivated manufactured by Beijing Institute of Biological Products, Co., Ltd.