Inclusion Criteria:  Healthy participants aged 18 years and above; Proven legal identity; The subjects can understand and voluntarily sign the informed consent form and be willing to complete the study in accordance with the study plan; Have received two doses of inactivated COVID-19 vaccine (CoronaVac®) manufactured by Sinovac Research & Development Co., Ltd and that is currently 5-9 months after the second dose.  Exclusion Criteria:  History of SARS-CoV-2 infection(laboratory confirmed); Have received three and more doses of inactivated COVID-19 vaccine; Known allergy to vaccines or vaccine ingredients, and serious adverse reactions to vaccines, such as urticaria, dyspnea, angioneurotic edema; Autoimmune disease such as systemic lupus erythematosus or immunodeficiency / immunosuppression such as AIDS, post-transplant; Severe chronic diseases, severe cardiovascular diseases, hypertension and diabetes that cannot be controlled by drugs, liver or kidney diseases, malignant tumors, etc; Severe neurological disease (epilepsy, convulsions or convulsions) or mental illness; Diagnosed abnormal blood coagulation function (eg, lack of blood coagulation factors, blood coagulopathy, abnormal platelets) or obvious bruising or blood coagulation; Immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids(excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) in the past 6 months; History of alcohol or drug abuse; Receipt of blood products within in the past 3 months; Receipt of other investigational drugs in the past 30 days; Receipt of attenuated live vaccines in the past 14 days; Acute diseases or acute exacerbation of chronic diseases within 7 days prior to booster vaccination; Axillary temperature >37.0°C; Participated in other clinical trials prior to enrollment and during the followup period, or planned to participate in other clinical trials during the clinical trial period; According to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.