Phase I Clinical Trial of Enterovirus Type71 - Coxsackievirus Type A16 Bivalent Vaccine

Inclusion Criteria: * Age Requirement: volunteers aged 6 months and 59 years. * Provision of Legal Identification: volunteers and their legal guardians or appointed representatives must provide valid legal identification documents. * Informed Consent: participants, legal guardians, or appointed representatives of volunteers must have the capacity to understand the informed consent document and the research process, voluntarily participate, sign the informed consent form, and be able to comply with the requirements in the study as well as complete relevant visits on time. * 6\~23months old: term delivery (gestational week 37 weeks \~ 42 weeks at birth), 2500g ≤ birth weight ≤ 4000g. * Requirements for contraception: agree to take contraception actions in 12 months. * Temperature Requirement: axillary body temperature is less than 37.3°C. Exclusion Criteria: Subjects meeting any of the following exclusion criteria will be not eligible for enrollment. * Subjects who have been allergic to any component of the vaccine in the past, or have any history of vaccine allergy or suspected allergy or other serious adverse reactions, such as urticaria, respiratory distress, and angioedema. * History of taking administration of a non-SARS-CoV-2 inactivated vaccine or subunit vaccine within 7 days before enrollment, or any live attenuated vaccine or SARS-CoV-2 vaccine within 14 days before enrollment. * Subjects with convulsion, epilepsy, encephalopathy, psychiatric history or family his…