A Study to Evaluate the Immunogenicity and Safety of EV71 Vaccine in Pediatric Subjects

Inclusion criteria

• Healthy children aged from 3 to 6 years old (i.e. ≥ 3 years old and < 7 years old) for Part A,and from 2 to 35 months old (i.e. ≥ 2 months old and < 36 months old) for Part B at the time of first vaccination.
• Subject's guardians are able and willing to comply with study procedures and provide the signed informed consent.
• Subject is able and can comply with the requirements of the protocol.
• Subject with body temperature ≤38°C.

Exclusion criteria

• Subject with previous known exposure to Enterovirus 71 (EV71).
• Subject with a history of herpangina, hand-foot-mouth disease,and acute hemorrhagic conjunctivitis associated with enterovirus infection in the past 3 months.
• Subject with gestation < 37 weeks.
• Subject with birth weight <2.5 kg.
• Subject with a history of hypersensitivity to vaccines, or a history of allergic disease or reactions likely to be exacerbated by any component of the vaccine.
• Family history of seizures or progressive neurological disease.
• Family history of congenital or hereditary immunodeficiency.
• Severe malnutrition or dysgenopathy.
• Major congenital defects or serious chronic illness, including perinatal brain damage.
• Subject diagnosed of having autoimmune disease (e.g., celiac disease, type I diabetes, lupus (SLE), juvenile dermatomyositis, scleroderma, juvenile idiopathic arthritis (JIA), immune (or idiopathic) thrombocytopenia purpura).
• Bleeding disorder diagnosed by a doctor or significant bruising or hemostatic difficulties with IM injections or blood draws.
• Any acute infections 7 days prior to administrating the first vaccination.
• Use of any investigational product (including drug, vaccine) within 30 days prior to vaccination or planned use during the study period.
• Administration of any vaccines within 14 days prior to randomization.
• Use of immunoglobulins or any blood products within 3 months prior to vaccination or planned use during the study period.
• Chronic administration (defined as > 14 days) of immunosuppressants or other immunomodulators or systemic corticosteroids within 6 months prior to vaccination or planned use during the study period.
• Subjects who had ever received investigational EV-71 vaccine prior to randomization.
• Under anti-tuberculosis prevention or therapy.
• Any condition that in the opinion of the investigator may interfere with the evaluation of study objectives.