* travel history / residence history of communities with case reports within 14 days prior to the study; * history of contact with a sars-cov-2 infection (positive in nucleic acid test) within 14 days prior to the study; * have contacted patients with fever or respiratory symptoms from communities with case reports within 14 days prior to the study; * two or more cases of fever and / or respiratory symptoms in a small contact area of volunteers, such as home, office etc. within 14 days prior to the study; * history of sars-cov-2 infection or receiving covid-19 vaccine; * 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, spleenlessness, functional spleenlessness, spleenlessness 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 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; * 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; * already pregnant (including a positive urine pregnancy test) or are breastfeeding, planning to get pregnant within 2 months; * 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.

* travel history / residence history of communities with case reports within 14 days prior to the study; * history of contact with a sars-cov-2 infection (positive in nucleic acid test) within 14 days prior to the study; * have contacted patients with fever or respiratory symptoms from communities with case reports within 14 days prior to the study; * two or more cases of fever and / or respiratory symptoms in a small contact area of volunteers, such as home, office etc. within 14 days prior to the study; * history of sars-cov-2 infection or receiving covid-19 vaccine; * 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, spleenlessness, functional spleenlessness, spleenlessness 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 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; * 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; * already pregnant (including a positive urine pregnancy test) or are breastfeeding, planning to get pregnant within 2 months; * 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.

- travel history / residence history of communities with case reports within 14 days prior to the study; - history of contact with a sars-cov-2 infection (positive in nucleic acid test) within 14 days prior to the study; - have contacted patients with fever or respiratory symptoms from communities with case reports within 14 days prior to the study; - two or more cases of fever and / or respiratory symptoms in a small contact area of volunteers, such as home, office etc. within 14 days prior to the study; - history of sars-cov-2 infection or receiving covid-19 vaccine; - 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, spleenlessness, functional spleenlessness, spleenlessness 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 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; - 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; - already pregnant (including a positive urine pregnancy test) or are breastfeeding, planning to get pregnant within 2 months; - 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.

- travel history / residence history of communities with case reports within 14 days prior to the study; - history of contact with a sars-cov-2 infection (positive in nucleic acid test) within 14 days prior to the study; - have contacted patients with fever or respiratory symptoms from communities with case reports within 14 days prior to the study; - two or more cases of fever and / or respiratory symptoms in a small contact area of volunteers, such as home, office etc. within 14 days prior to the study; - history of sars-cov-2 infection or receiving covid-19 vaccine; - 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, spleenlessness, functional spleenlessness, spleenlessness 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 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; - 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; - already pregnant (including a positive urine pregnancy test) or are breastfeeding, planning to get pregnant within 2 months; - 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.