Immunogenicity of the Inactivated EV71 Vaccine Combined With Hepatitis B and Group A Meningococcal Vaccine

Inclusion Criteria: * Healthy children aged 6-7 months with no history of vaccination within the past month and normal intelligence. * Healthy individuals determined by researchers after inquiring about medical history and physical examination. * The recipients are able to comply with the requirements of the research protocol and undergo immunogenicity testing. * Individuals without contraindications. * Underarm temperature ≤ 37 ℃. * Obtain informed consent from the recipient's guardian and sign an informed consent form. Exclusion Criteria: * Individuals with any serious illness. * Individuals who are allergic to any ingredient in the research vaccine. * Individuals with a history of neurological symptoms or signs. * Individuals with bleeding constitution or prolonged bleeding time. * Individuals who have had hand, foot, and mouth disease, hepatitis B, and epidemic cerebrospinal meningitis in the past. * Individuals who have received other vaccines or immunoglobulin injections or any investigational drugs within the past 4 weeks. * Infected individuals who have had any acute illness or require systemic antibiotic or antiviral treatment within the past 7 days. * Individuals who have experienced fever (axillary temperature ≥ 38 ℃) within the past 3 days. * Participating in another researcher. * Individuals with a history or family history of allergies, seizures, epilepsy, encephalopathy, and mental illness. * Patients with thrombocytopenia or other coagulation disorders that may cause contraindications for intramuscular injection. * Patients with severe chronic diseases. * Known or suspected concurrent diseases include: respiratory system diseases, acute or chronic disease activity period, HIV infection in the mother or research subject of the child, cardiovascular disease, severe hypertension, malignant tumor treatment period, and skin disease patients. * Endemic disease patients. * Those who plan to leave their place of residence before the end of the study. * Researchers believe that any situation that may affect observation and evaluation.