Study on the Immune Effect of a Domestic Inactivated Hepatitis A Vaccine Among Healthy Children

Objective To evaluate the immunogenicity and immune persistence of a Chinese domestic hepatitis A vaccine,inactivated(HepA-I) among children. Methods A randomized double blind clinical trial was conducted in Wujin District of Changzhou city in 213 healthy children aged from 2 to 8 years and with negative antibodies to hepatitis A virus(Anti-HAV).After they had completed two doses of full immunization of HepA-I,they were observed for 5 years.The dosage of the domestic trail HepA-I was 250 unit(U) /0.5ml and the dosage of the imported control HepA-I was 720 enzyme linked immunosorbent assay unit(Elu)/0.5ml.The ratio of the subjects receiving the trial vaccine to those receiving the control vaccine was 3:1.Anti-HAV titers were determined 1,6 and 7 months and 1 to 5 years after the full immunization. Results One month and one to four years after the full vaccination,the seroconversion rates of the trial group and the control group were both 100%.In the 5th year,the seroconversion rates were 99.1% and 97.3%,respectively.The geometric mean concentrations(GMCs) of the trial group and the control group in the 1st month after the full vaccination were 4,079.6 mIU/ml and 1,394.6 mIU/ml,respectively,and dropped to 308.2 mIU/ml and 195.1 mIU/ml in the 5th year,both indicating statistical differences(t=6.577,P0.001;t=2.748,P=0.007,respectively). Conclusions The domestic inactivated hepatitis A vaccine has a sound immunogenicity and immune persistence after two doses of full immunization among children.