* history of sars-cov-2 infection(laboratory confirmed); * those who have received covid-19 vaccine from other manufacturers other than sinovac research\& development co., ltd., or who have received booster immunization with covid-19 vaccine after two doses of covid-19 vaccine (vero cell),inactivated manufactured by sinovac research\& development co., ltd.; * history of serious adverse reactions to the vaccine or vaccine components, such as urticaria dyspnea and angioneuroedema; * autoimmune disease or immunodeficiency/immunosuppression; * 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; * immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids(excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) in the past 6 months or plan to receive these treatments during the study period; * receipt of blood products within in the past 3 months or plan to receive these treatments during the study period; * receipt of other investigational drugs in the past 30 days; * receipt of attenuated live vaccines in the past 14 days,or receipt of inactivated or subunit vaccines in the past 7 days; * onset of various acute or chronic diseases within 7 days prior to the study; * axillary temperature \>37.0°c; * 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); * those who have received covid-19 vaccine from other manufacturers other than sinovac research\& development co., ltd., or who have received booster immunization with covid-19 vaccine after two doses of covid-19 vaccine (vero cell),inactivated manufactured by sinovac research\& development co., ltd.; * history of serious adverse reactions to the vaccine or vaccine components, such as urticaria dyspnea and angioneuroedema; * autoimmune disease or immunodeficiency/immunosuppression; * 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; * immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids(excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) in the past 6 months or plan to receive these treatments during the study period; * receipt of blood products within in the past 3 months or plan to receive these treatments during the study period; * receipt of other investigational drugs in the past 30 days; * receipt of attenuated live vaccines in the past 14 days,or receipt of inactivated or subunit vaccines in the past 7 days; * onset of various acute or chronic diseases within 7 days prior to the study; * axillary temperature \>37.0°c; * 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); those who have received covid-19 vaccine from other manufacturers other than sinovac research& development co., ltd., or who have received booster immunization with covid-19 vaccine after two doses of covid-19 vaccine (vero cell),inactivated manufactured by sinovac research& development co., ltd.; history of serious adverse reactions to the vaccine or vaccine components, such as urticaria dyspnea and angioneuroedema; autoimmune disease or immunodeficiency/immunosuppression; 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; immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids(excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) in the past 6 months or plan to receive these treatments during the study period; receipt of blood products within in the past 3 months or plan to receive these treatments during the study period; receipt of other investigational drugs in the past 30 days; receipt of attenuated live vaccines in the past 14 days,or receipt of inactivated or subunit vaccines in the past 7 days; onset of various acute or chronic diseases within 7 days prior to the study; axillary temperature >37.0°c; 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); those who have received covid-19 vaccine from other manufacturers other than sinovac research& development co., ltd., or who have received booster immunization with covid-19 vaccine after two doses of covid-19 vaccine (vero cell),inactivated manufactured by sinovac research& development co., ltd.; history of serious adverse reactions to the vaccine or vaccine components, such as urticaria dyspnea and angioneuroedema; autoimmune disease or immunodeficiency/immunosuppression; 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; immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids(excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) in the past 6 months or plan to receive these treatments during the study period; receipt of blood products within in the past 3 months or plan to receive these treatments during the study period; receipt of other investigational drugs in the past 30 days; receipt of attenuated live vaccines in the past 14 days,or receipt of inactivated or subunit vaccines in the past 7 days; onset of various acute or chronic diseases within 7 days prior to the study; axillary temperature >37.0°c; according to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.