A Phase II Clinical Trial for Inactivated Vaccine (Vero Cell) Against EV71 in Chinese Children and Infants

Inclusion Criteria: For children group (aged from 12-36 months): * Healthy children aged from 12 to 36 months old as established by medical history and clinical examination * The subjects' guardians are able to understand and sign the informed consent * Had never received the vaccine against EV71 * Subjects who can and will comply with the requirements of the protocol * Subjects with temperature \<=37.0°C on axillary setting For infants group (aged from 6-11 months): * Healthy infants aged from 6 to 11 months old as established by medical history and clinical examination * The subjects' guardians are able to understand and sign the informed consent * Had never received the vaccine against EV71 * Subjects who can and will comply with the requirements of the protocol * Subjects with temperature \<=37.0°C on axillary setting Exclusion Criteria: For children group (aged from 12-36 months): * Subject who has a medical history of HFMD * \<= 37 weeks gestation * Subjects with a birth weight \<2.5 kg * Subject that has a medical history of any of the following: allergic history, or allergic to any ingredient of 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 * Autoimmune disease * Bleeding disorder diagnosed by a doctor or significant bruising or bleeding difficulties with IM injections or blood draws * Any acute infections in last 7 days * Any prior administration of immunodepressant or corticosteroids in last 6month * Any prior administration of blood products in last 3 month * Any prior administration of other research medicines in last 1 month * Any prior administration of attenuated live vaccine in last 28 days * Any prior administration of subunit or inactivated vaccines in last 14 days, such as pneumococcal vaccine * Under the anti-TB prevention or therapy * Any condition that in the opinion of the investigator, may interfere with the evaluation of study objectives For infants group (aged from 6-11 months): * Subject who has a medical history of HFMD * \<= 37 weeks gestation * Subjects with a birth weight \<2.5 kg * Subject that has a medical history of any of the following: allergic history, or allergic to any ingredient of 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 * Autoimmune disease * Bleeding disorder diagnosed by a doctor or significant bruising or bleeding difficulties with IM injections or blood draws * Any acute infections in last 7 days * Any prior administration of immunodepressant or corticosteroids in last 6month * Any prior administration of blood products in last 3 month * Any prior administration of other research medicines in last 1 month * Any prior administration of attenuated live vaccine in last 28 days * Any prior administration of subunit or inactivated vaccines in last 14 days, such as pneumococcal vaccine * Under the anti-TB prevention or therapy * Any condition that in the opinion of the investigator, may interfere with the evaluation of study objectives Exclusion Criteria for the second dose: * Had any Grade 3 or Grade 4 adverse reaction within 7 days after first dose * Any situation meet the exclusion criteria stated in the exclusion criteria for first dose * Had any SAE related to first dose during the following-up of first dose * Any condition that in the opinion of the investigator, or IRB