[Immunogenicity and efficacy of two live attenuated hepatitis A vaccines (H(2) strains and LA-1 strains)].
OBJECTIVE
To assess the efficacy and immunogenicity of two live attenuated hepatitis A vaccines.


METHODS
Randomized and controlled clinical trials were conducted in Guanxi, Hebei and Shanghai, 457 251 children were enrolled. The efficacy for preventing clinical hepatitis A was calculated by the comparison of incidence rate of disease between vaccine group and control group. Susceptible subjects tested anti-HAV negative before the study were followed up after vaccination for determination of the immunogenicity and vaccine efficacy to prevent subclinical infection.


RESULTS
The protective efficacy to prevent clinical infection by both H(2) and LA-1 vaccines were 95%. The peak of seroconversion was observed in 94.9% and 86.0% respectively for the two vaccines. The seroconversion rate decreased to 75% approximately 80% in the third year, but the vaccine protection against clinical hepatitis A has remained unchanged throughout the 3 years.


CONCLUSIONS
Both strains of the live attenuated hepatitis A vaccines have good immunogenicity and high protection against clinical disease, the efficacy to prevent subclinical infection is not significant. The subclinical HAV infection serves as a natural booster for the vaccinees.
Xu
Zhiyi
Z
Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, China.
Wang
Xuanyi
X
Li
Rongcheng
R
Meng
Zongda
Z
Zhang
Yong
Y
Gong
Jian
J
Ma
Jingchen
J
Li
Yanting
Y
Zhao
Shoujun
S
Li
Yanping
Y
Zhao
Yuliang
Y
Huang
Quancheng
Q
Luo
Dong
D
Xia
Jianling
J
Liu
Hongbin
H
Liu
Xinli
X
Ouyang
Peiying
P
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D006506:Hepatitis A / Q000276:immunology / Q000517:prevention & control*; D022362:Hepatitis A Vaccines / Q000008:administration & dosage* / Q000276:immunology; D006801:Humans; D008297:Male; D016896:Treatment Outcome; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology
D022362:Hepatitis A Vaccines; D014613:Vaccines, Attenuated