The effects of booster vaccination of hepatitis B vaccine on anti-HBV surface antigen negative children 11-15 years after primary vaccination.

The twin aims of this study were to investigate the changes in anti-HBs IgG levels after booster vaccinations and to compare the effects of different vaccine doses in children aged 11-15 years who were both negative for HBsAg and had an Anti-HBs < 10.0 mIU/mL after primary vaccination. Children who were born between 1993 and 1998 and who had completed their Hepatitis B vaccination program in infancy were randomly recruited to the study. The participants were divided into three groups according to their anti-HBs IgG levels: group I had a level < 0.1 mIU/mL; group II 0.1 - < 1.0 mIU/mL, and group III 1.0 - < 10.0 mIU/mL. The booster vaccination program comprised three (20μg) doses of HepB (CHO) vaccine administered at zero, one and six months after they are join this program: anti-HBs levels were measured one month after the first and third vaccinations. Among 448 HBsAg-negative infants, anti-HBs seroconversion rates (defined as an anti-HBs >= 10 mIU/mL) after the first and third vaccinations were 85.5% and 98.6% respectively - these observed differences were statistically significant (χ2 [1dof] = 50.11, p< 0.05). Seroconversion rates and GMTs after the first and third doses were significantly lower for group I children than the other two groups (p< 0.05). Compared, the OR of being negative (anti-HBs< 10mIU/ml) in group I after the first and the third dose were 7.66 (95%CI: 4.35-13.47, P< 0.05) and 20.48 (95% CI: 2.36-177.67, P< 0.05). So the anti-HBs titer levels decay to 10mIU/ml in 11-15 years of age children completed HepB Basic immunization, which need for booster immunization. The effect is better for those children with a relatively higher antibody titer before booster, and the effect of three doses booster is best.