This study is a multi-center and open design, phase Ⅳ clinical trial in population aged 3~17 years . The experimental vaccine will be manufactured by Sinovac Research and Development Co.,Ltd.The study is planned to be carried out in 11 provinces from August 2021 to December 2022, including Liaoning, Heilongjiang, Anhui, Fujian, Jiangxi, Hubei, Guangxi, Chongqing, Guizhou, Yunnan and Gansu. Each province will serve as a research center, and each research center will select the corresponding research site.A total of 33000 subjects including patients with pre-existing will be enrolled with 3000 for each research center, including 600 subjects aged 3~5years，1200 subjects aged 6~11 years,1200 subjects aged 12~17 years.~And subjects will receive two doses of vaccine on day 0 and day 28.
This study is a multi-center and open design, phase Ⅳ clinical trial of an inactivated SARS-CoV-2 vaccine (CoronaVac) manufactured by Sinovac Research and Development Co., Ltd.The purpose of this study is to evaluate the safety of the SARS-CoV-2 Inactivated vaccine in population aged 3~17 years and in people with pre-existing disease to provide reference for improving the immunization strategy of COVID-19 vaccine.