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 18 years years and older and in people with pre-existing disease to provide reference for improving the immunization strategy of COVID-19 vaccine.

This study is a multi-center and open design, phase Ⅳ clinical trial in population aged 18 years years and older. 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 May 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 121000 subjects will be enrolled with11000 for each research center, including at least 2000 people with pre-existing disease and at least 4000 people in the elderly group (60 years old and above) (including patients with pre-existing disease).And subjects will receive two doses of vaccine on day 0 and day 28.

Inclusion Criteria:

• Have not received any COVID-19 vaccine in the past or at least one dose of CoronaVac manufactured by Sinovac Research and Development Co.,Ltd;
• Population aged 18 years and above;
• The subjects can understand and voluntarily sign the informed consent form and participate in the follow-up;

Exclusion Criteria:

• History of severe allergy to the vaccine such as acute allergic reaction,angioedema and dyspnea ;
• Severe neurological disease such as transverse myeliti,Guillain-Barre Syndrome and demyelinating disorders;
• Acute diseas,acute onset of chronic disease and severe chronic diseases.