Immunogenicity And Safety of COVID-19 Vaccine , Inactivated Co -Administration With EV71 Vaccine (Vero Cell)

Inclusion Criteria:

- Children aged 3-5 years ;

- The subject and/or guardian can understand and voluntarily sign the informed consent
form

- Proven legal identity;

Exclusion Criteria:

- 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.