This is a multi-center, case-driven, randomized, double-blinded, and placebo-controlled Phase Ⅲb clinical trial of COVID-19 Vaccine manufactured by Sinovac Research & Development Co., Ltd.The purpose of this study is to evaluate the efficacy of the booster dose after two doses of CoronaVac® against RT-PCR confirmed symptomatic COVID-19 cases in participants aged 18 years and above.A total of 13,800 participants aged 18 years and above, who have received 2 doses CoronaVac® in an interval between 21-56 days will be enrolled.Participants will be enrolled and randomly assigned into 3 groups at a ratio of 1:1:1 to receive a booster dose of medium-dose or high-dose COVID-19 Vaccine or placebo 5-8 months after their second dose.Efficacy assessments will include the surveillance for COVID-19-like symptoms, the laboratory confirmation of SARS-CoV-2 infection by RT-PCR, and recording of COVID-19-related hospitalizations.All participants will be monitored for immediate reactions (within 30 minutes) after the booster dose vaccination, adverse events of special interest (AESIs) and serious adverse events (SAEs) for 6 months after booster dose inoculation. In addition,participants in reactogenicity subgroup will be monitored for local and systemic solicited adverse events (AEs) within 7 days and the unsolicited AEs within 28 days.Immunogenicity assessments will be determined by neutralizing and anti-SARS-CoV-2 S-protein antibodies in subgroup participants. The participants in the immunogenicity subgroup will be in the reactogenicity subgroup as well.
This is a multi-center, case-driven, randomized, double-blinded, and placebo-controlled Phase Ⅲb clinical trial of COVID-19 Vaccine manufactured by Sinovac Research & Development Co., Ltd.The purpose of this study is to evaluate the efficacy of the booster dose after two doses of CoronaVac® against RT-PCR confirmed symptomatic COVID-19 cases in participants aged 18 years and above.