To evaluate the safety and immunogenicity of Hepatitis A (Live) Vaccine, Freeze-dried produced by Changchhun Institute of Biological Products Co., Ltd, we design this randomized, parallel controlled study. 450 subjects are divided into 3 groups, including 1 experimental group and 2 control groups (Research Group 1, 2, and 3), each group assigned 150 subjects respectively.~All subjects are aged 18-24 months old.~150 subjects from Research Group 1 will be administrated with one dose of Hepatitis A (Live) Vaccine, Freeze-dried produced by Changchhun Institute of Biological Products Co., Ltd. Blood samples are collected before vaccination and one month (30 days) later.~150 subjects from Research Group 2 will be administrated with one dose of Hepatitis A（Live）Vaccine，Freeze-dried produced by Zhejiang Pukang Biotechnology Co., Ltd. Blood samples are collected before vaccination and one month (30 days) later.~150 subjects from Research Group 3 will be administrated with one dose of Hepatitis A (Live) Vaccine, Freeze-dried produced by Institute of Medical Biology, Chinese Academy of Medical Sciences. Blood samples are collected before vaccination and one month (30 days) later.~To evaluate the immunogenicity, we will detect and compare the seroconversion rates, and antibody geometric mean concentrations. The safety of all groups will be monitored as well.
Subjects will be recruited and divided into 3 groups:~Hepatitis A（Live）Vaccine，Freeze-dried produced by Changchun Institute of Biological Products Co., Ltd~Hepatitis A（Live）Vaccine，Freeze-dried produced by Zhejiang Pukang Biotechnology Co., Ltd., and~Hepatitis A（Live）Vaccine，Freeze-dried produced by Institute of Medical Biology, Chinese Academy of Medical Sciences.~After immunization, the immunogenicity and safety of three different manufacturers will be compared and the data will be analyzed.