A Clinical Study to Evaluate the Safety and Immunogenicity of the Recombinant COVID-19 Vaccine (Sf9 Cell) as a Booster in People Aged 18-60 Years

A observer-blind, randomized, controlled, investigator-initiated clinical trial to evaluate the safety and immunogenicity of a booster vaccination with Recombinant COVID-19 vaccine (Sf9 Cell) in a population aged 18-60 years old who have completed 3 doses vaccination with COVID-19 Vaccine (Vero Cell), Inactivated ≥ 6 months at least 6 months prior to enrolment. The study uses a non-inferiority design to compare between schedules with Recombinant COVID-19 Vaccine (Sf9 Cell) versus COVID-19 Vaccine (Vero Cell) Inactivated as the booster dose. Participants, laboratory and analysing statisticians will remain blind to treatment allocation. A total of 120 participants will be enrolled, participants will be randomized 1:1 to receive a single dose of Recombinant COVID-19 vaccine (Sf9 Cell) (test group) or COVID-19 Vaccine (Vero Cell), Inactivated.