This study aims to evaluate the safety, reactogenicity and immunogenicity of EV71 vaccine in health children and infants aged from 2 months to <12yrs.

Main Inclusion Criteria:

1. Healthy children and infants aged from 2 months to less than 12 years as established by medical history and clinical examination
2. The subjects' guardians are able to understand and sign the informed consent

Main Exclusion Criteria:

1. Subject with previous known exposure to EV71.
2. Subject with a history of herpangina or hand, foot and mouth disease associated with enterovirus infection in the past 3 months.
3. Subject who was diagnosed with a significant neurological, pulmonary, cardiovascular, hematological, hepatic or renal disorder.
4. Use of any investigational/non-registered product (including drug, vaccine and invasive medical device) within 30 days prior to vaccination or planned use during study period.
5. Subject with any confirmed or suspected autoimmune disorder, or immunodeficiency
6. Use of immunoglobulins or any blood products within 3 months prior to vaccination or planned use during the whole study period.