Hepatitis B virus (HBV) infection during fetal, perinatal period, and infan-cy is known to progress frequently to the chronic HBV carrier state. In endemic zones such as in Korea, in fact, chronic HBV carriers mainly stem from HBV infection in their fetal, perinatal period and infancy. Therefore, appropriate preventative measure from the period immediately after birth is most desirable to prevent subsequent HBV carrier state, which correlates highly with the development of chronic hepatitis, cirrhosis, and even primary hepatocellular carcinoma later in life.
Thus, the author administered HBV vaccine to 101 newborn infants born at Hanyang University Hospital, using Hevac B 5?g HBsAg/ml, Pasteur In-stitute, France) at 0.5m1(2.5?g HBsAg) per dose, a half of the recommended adult dose. The basic vaccinations were given three times, at birth, 1 month, and 2 months, with a booster vaccination at 14 months of age. Blood samples were drawn at birth before the first vaccination, 2 months, 4 months, 14 mon-ths and 16 months. And samples were tested for HBsAg, antibody to HBsAg (anti-HBs) and anti-HBc by radioimmunoassays (RIA) (AUSTRIA® AUSAB®, CORAB® kit, Abbott Lab).
The following results of the study were obtained from the observation over the 16 months period:
1. 51.5% (52/101) showed anti-HBs positivity at birth from the maternal transmission.
2. The HBsAg positivity was observed in 6 infants out of total 101 infants. All infants were HBsAg negative at birth, but HBsAg positivity was observed in 2 infants at 2 months, in 3 infants at 4 months, and in one other additional infant at 14 months.
3. In the infants negative for anti-HBs at birth, the anti-HBs positivity rate at 2 months after birth, e.g. after second vaccination was 20%; at 4 mon-ths, e.g. after third vaccination, 67.7%; at 14 months and 16 months, 84.4%. Meanwhile, in the infants positive for passively acquired anti-HBs . at birth, the anti-HBs positivity rate at 2 months after birth, e.g. after se-cond vaccination was 7.1%; at 4 months, e.g. after third vaccination, 75.8%; at 14 months and 16 months 84.8%. As the two groups were com-bined, the total positivity rate at 2 months, e.g. after second vacination, was 13.4%; at 4 months, e.g. after third vaccination, 71.9%; at 14 months, 83.1%; at 16 months e.g. after booster vaccination, 84.6%. The presence of the maternally transmitted anti-HBs seemed to show no significant dif-ference in the efficacy of the active immunization.
4. The maternally transmitted anti-HBc positivity rate at birth was 56.4 % (57/101). In the infants positive for anti-HBc, the anti-HBc remained positive in 93.2% at 2 months; 81.1% at 4 months; 5.6% at 1.4 months; 0% after 16 months, indicating almost complete loss of the positivity by one year.
5. In the infants negative for anti-HBs at birth, the antibody titer after se-cond vaccination was 1.4 (1.1-1.6) mIU/ml; after third vaccination, 12 (5-28) mIU/ml; at 14 months at booster vaccination, 18 (8-41) mIU/ml; at 16 months after booster 185 (44-786) mIU/ml, indicating an anamnestic response after the booster vaccination.
6. The significant rise in the titer of anti-HBs after the booster vaccination was noted in 77.8% (35/45). The titer before the booster was 42 (23-76) mIU/ml, while the titer after the booster was 638 (318-1279) mIU/ml, in-dicating the rapid rise in the titer after the booster. Therefore, the booster is considered imperative for the efficacy of Hepatitis B active immuniza-tion.
7. The anti-HBs positive response at 14 months and 16 months following the HBV vaccination schedule was observed in 84.6% (55/65) and negative response in 15.4% (10/65)
8. The study proves the efficacy of the active immunization for the newborn infants in preventing HBV infections. The result of the study is con-sidered to justify the enforcement of the HBV vaccination in conjunction with the routine active immunization schedule for all the newborn infants in the endemic zone at high risk for HBV infection, such as in Korea.
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