* history of sars-cov-2 infection(laboratory confirmed); * have received inactivated sars-cov-2 vaccine from other manufacturers other than sinovac life sciences co., ltd.,beijing institute of biological products co.,ltd.and wuhan institute of biological products co.,ltd.and received three and more doses of inactivated sars-cov-2 vaccine; * severe adverse reactions, such as urticaria, dyspnea, and angioneurotic edema , occurred during the primary immunization; * 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 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; * already pregnant or are breastfeeding, planning to get pregnant within 1months (according to subjects' self-report and urine pregnancy test results); * 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.

* history of sars-cov-2 infection(laboratory confirmed); * have received inactivated sars-cov-2 vaccine from other manufacturers other than sinovac life sciences co., ltd.,beijing institute of biological products co.,ltd.and wuhan institute of biological products co.,ltd.and received three and more doses of inactivated sars-cov-2 vaccine; * severe adverse reactions, such as urticaria, dyspnea, and angioneurotic edema , occurred during the primary immunization; * 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 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; * already pregnant or are breastfeeding, planning to get pregnant within 1months (according to subjects' self-report and urine pregnancy test results); * 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.

history of sars-cov-2 infection(laboratory confirmed); have received inactivated sars-cov-2 vaccine from other manufacturers other than sinovac life sciences co., ltd.,beijing institute of biological products co.,ltd.and wuhan institute of biological products co.,ltd.and received three and more doses of inactivated sars-cov-2 vaccine; severe adverse reactions, such as urticaria, dyspnea, and angioneurotic edema , occurred during the primary immunization; 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 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; already pregnant or are breastfeeding, planning to get pregnant within 1months (according to subjects' self-report and urine pregnancy test results); 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.

history of sars-cov-2 infection(laboratory confirmed); have received inactivated sars-cov-2 vaccine from other manufacturers other than sinovac life sciences co., ltd.,beijing institute of biological products co.,ltd.and wuhan institute of biological products co.,ltd.and received three and more doses of inactivated sars-cov-2 vaccine; severe adverse reactions, such as urticaria, dyspnea, and angioneurotic edema , occurred during the primary immunization; 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 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; already pregnant or are breastfeeding, planning to get pregnant within 1months (according to subjects' self-report and urine pregnancy test results); 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.