Comparison of Two-year Follow-up Immunogenicity Between Live Attenuated Hepatitis A Vaccine and Imported Inactivated Vaccine

Objective To compare immune efficacy of live attenuated hepatitis A vaccine with that of inactivated vaccine.Methods These 217 children aged 6-12 years with negative anti-HAVIg G at the enrollment from Liucheng county of Guangxi Zhuang autonomous region were randomized into 4 groups.Groups B and C received the LA-1 strain,a live attenuated HAV vaccine(10^{6.7550,Changchun Institute of Biology Products)according to schedules of 0-6 months and 0-12 months respectively.106.0TCID₅₀ live attenuated HAV vaccine was administered to group D,and inactivated hepatits A vaccine(HavrixTM,720 E1.U,SKB)to group E both at 0,6 month follow-up bloods were taken at month,6,12,24 after the first dose and 1 month after the second dose for all groups with additional samples at month 1 for Group D and E.All samples were tested for anti-HAVIg G using Imx mEIA kit(Abbott Lab.).Results During follow-up,in both schedules,live attenuated vaccine had similar effective seroconversion rates and antibody titers as inactivated vaccine at all points of time except for that of the 0-6 months schedule at 1 month after the booster.In group D with lower dose live attenuated vaccine,the anti-HAV positive rate and level were lower than those in the other groups.Conclusion A high dose of attenuated live HAV vaccine with a booster dose was similar to the inactivated vaccine in immunity effect,demonstrating a good immunogenicity and memory.Booster dose will ensure long-term protection against HAV.}