This study is a phase 4 clinical trial to evaluate the immunogenicity,safety and cross-immune response of booster immunization using COVID-19 vaccine，to compare the similarities and differences of immune responses between primary immunization and booster immunization and to detect antibody against hepatitis A and evaluate the immune persistence of the one dose immunization schedule of hepatitis A vaccine in healthy population aged 18 years and older. The experimental vaccine is manufactured by Sinovac Life Sciences Co., Ltd.. A total of 180 healthy subjects received two dose of inactivated COVID-19 vaccine (CoronaVac) based on primary immunization in previous Phase Ⅳ clinical trial will be enrolled, including 90 adults aged 18-59 years and 90 elderly elderly aged 60 years and older.Subjects in each age group will receive the booster immunization of CoronaVac(the third dose) and will be collected blood sample before booster immunization and 14 days after booster immunization.
This is a phase Ⅳ follow-up clinical trial based on the previous Phase Ⅳ clinical trial of an inactivated COVID-19 vaccine (CoronaVac) manufactured by Sinovac Life Sciences Co., Ltd.The purpose of this study is to evaluate the immunogenicity,safety and cross-immune response of booster immunization using COVID-19 vaccine,to compare the similarities and differences of immune responses between primary immunization and booster immunization and to detect antibody against hepatitis A and evaluate the immune persistence of the one dose immunization schedule of hepatitis A vaccine in healthy population aged 18 years and older.