[Persistence of HB vaccine immune protection and response to hepatitis B booster immunization].
OBJECTIVE
To determine the persistence of immune protection of China-made, plasma-derived HBV vaccine in infants and the time table of booster immunization.


METHODS
Serological effect of 7-year follow-up study and antibody response of an experimental study on booster were detected using radioimmunoassay.


RESULTS
The protective anti-HBs positive rates of 1,018 children, who were vaccinated according to the regimen of three doses of 10 micrograms HBV vaccine, declined from 75.0% during the first two years to 48.2% at 7 years after the first dosages, however, the positive rates for HBsAg and anti-HBc always fluctuated at low frequency. 144 children aged 6 or 7 years old, who received the HBV vaccine in their infancy and were negative for both HBsAg and anti-HBc before booster, were selected from 1,018 children of the follow-up study and boosted with 1 microgram (intradermally) or 2 micrograms (hypodemically) HBV vaccine. Their anti-HBs GMT and anti-HBs positive rate were 190.6 mIU/ml and 89.6% at one 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% at 12th month; among 65 children with the anti-HBs negative before booster, 40 of them had the level of anti-HBs > or = 100 mIU/ml one month after booster, suggesting the retention of immunological memory in most of them.


CONCLUSIONS
No need for revaccination against hepatitis B at 7th year after the initial immunization due to better persistence of immune protection of the vaccine.
Li
H
H
Institute of Basic Medical Sciences, CAMS and PUMC, Beijing 100005.
Li
R
R
Liao
S
S
Yang
J
J
Zeng
X
X
D002648:Child; D002675:Child, Preschool; D005500:Follow-Up Studies; D006509:Hepatitis B / Q000517:prevention & control*; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000097:blood; D017325:Hepatitis B Vaccines / Q000276:immunology*; D006801:Humans; D007117:Immunization, Secondary; D007223:Infant; D014611:Vaccination
D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines