Published online Dec 15, 1998. doi: 10.3748/wjg.v4.i6.493
Revised: November 20, 1998
Accepted: December 5, 1998
Published online: December 15, 1998
AIM: To identify the persistence of immune protection of China-made, plasma-derived hepatitis B vaccine after infancy immunization and the time table of booster immunization.
METHODS: A cross-sectional follow-up study and an experimental study on booster were used for the evaluation of the serological effect 7 years after vaccination and the antibody anamnestic response. Radioimmunoassay was used for the detection of hepatitis B virus markers.
RESULTS: The protective anti-HBs positive rates of 1018 children, who were vaccinated according to the regimen of three doses of 10 μg hepatitis B vaccine in their infancy, declined from 75.0% during the first two years to 48.2% in the 7th year after the first dosage, however, the positive rates for HBsAg and anti-HBc always fluctuated at a low frequency. A total of 144 subjects aged 6 or 7 years, who were negative for both HBsAg and anti-HBc before booster, were selected from 1018 children of the follow-up study, and boosted with 1 μg intradermally or 2 μg hypodermically hepatitis B vaccines. Their anti-HBs GMT and anti-HBs positive rates were 190.6 mIU/mL and 89.6% in the first month after booster, significantly higher than 14.7 mIU/mL and 54.9% before booster (P < 0.01), and declined back to 25.3 mIU/mL and 75.5% in the 12th month; among 65 children with the anti-HBs negative before booster, 40 had a level of anti-HBS ≥ 100 mIU/mL one month after booster, suggesting retention of immune memory in most of them.
CONCLUSION: No need for revaccination against hepatitis B in the 7th year after the initial immunization due to better persistence of immune protection of the vaccine and retention of immune memory to hepatitis B virus in the vast majority of the vaccinees.