Immunogenicity and Safety of Enterovirus Type 71 Vaccine,Inactivated(Vero Cells) in Volunteers Aged From 6 to 71 Months

Inclusion Criteria: * Age 6-71 months, valid identification; * Infants aged 6-11 months should be full-term (37-42 weeks gestation) and have a birth weight (2500g≤ weight ≤4000g); * The subject's guardian voluntarily consented to the child's participation in the study and signed an informed consent form; * The subject's guardian had the ability to learn about the study procedure and was able to participate in all planned follow-ups; * Pre-enrollment axillary body temperature \< 37.5°C. Exclusion Criteria: * Have received any previous HFMD vaccine; * Previous history of hand, foot and mouth disease； * History of allergies to any component of the study vaccine or substances used in the preparation process，or a history of severe adverse effects of vaccine/drug； * Have a serious congenital malformation or chronic medical condition that may interfere with the conduct or completion of the study； * History of seizures, epilepsy, encephalopathy, and psychosis (including family history)； * Have contraindications to intramuscular injections such as thrombocytopenia, any coagulopathy, or being treated with anticoagulants； * Have an infectious disease with clinical or serological evidence； * Patients with asplenia, splenectomy, or functional asplenia due to any condition； * Patients with congenital or acquired immunodeficiency; or receive systemic corticosteroids within 3 months prior to enrollment, or be on other immunosuppressants prior to enrollment； * Have received treatment with …