- history of contact with a sars-cov-2 infection (positive in nucleic acid test) within 14 days; - history of multiple system inflammatory syndrome (mis-c); - history of hand, foot and mouth disease, herpetic angina or ev71 vaccination; - history of asthma, history of allergy to the vaccine or vaccine components,or serious adverse reactions to the vaccine, such as urticaria, dyspnea,and angioedema; - congenital malformations or developmental disorders, genetic defects,severe malnutrition, etc.; - autoimmune disease (systemic lupus erythematosus)or immunodeficiency / immunosuppression(hiv,history after organ transplantation); - 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; - thyroid disease or history of thyroidectomy, asplenia,functional asplenia, asplenia or splenectomy resulting from any condition; - 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 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; - receipt of inactivated or subunit vaccines in the past 7 days; - severe neurological disease (epilepsy, convulsions or convulsions) or mental illness; - axillary temperature >37.0°c; - the subjects participated in other clinical trials during the follow-up period,or will be planned within 3 months; - according to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.

- history of contact with a sars-cov-2 infection (positive in nucleic acid test) within 14 days; - history of multiple system inflammatory syndrome (mis-c); - history of hand, foot and mouth disease, herpetic angina or ev71 vaccination; - history of asthma, history of allergy to the vaccine or vaccine components,or serious adverse reactions to the vaccine, such as urticaria, dyspnea,and angioedema; - congenital malformations or developmental disorders, genetic defects,severe malnutrition, etc.; - autoimmune disease (systemic lupus erythematosus)or immunodeficiency / immunosuppression(hiv,history after organ transplantation); - 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; - thyroid disease or history of thyroidectomy, asplenia,functional asplenia, asplenia or splenectomy resulting from any condition; - 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 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; - receipt of inactivated or subunit vaccines in the past 7 days; - severe neurological disease (epilepsy, convulsions or convulsions) or mental illness; - axillary temperature >37.0°c; - the subjects participated in other clinical trials during the follow-up period,or will be planned within 3 months; - according to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.