Most of the perinatally infected infants from their HBsAg carrier mothers become chronic carrier and develop chronic liver disease. Prevention of vertical transmission is most important in elliminating hepatitis B virus infection. CDC recommended passive and early active immunization in neonatal infants born to HBsAg carrier mothers to prevent perinatal vertical transmission.
The author checked anti-HBs titer at 7~9 month of age in 112 infants who were born to HBsAg carrier mothers and were received HBIG 0.5cc at birth and 0.5cc Hepavax at 0, 1, 6 month of age by CDC recommendation and studied the preventive effect of passive and early active immunization.
The results were as follows :
1) Anti-HBs was positive in 98 infants(87.5%) and negative in 14 infants(l2.5%). Because 6 positive infants had anti-HBs below 10mIU/ml. only 92 infants(82.1%) had minimal protective anti-HBs.
2) Anti-HBs positive rate in infants of HBeAg (+) mothers was 77.8% (35/45) which was significantly lower than 94.0% (63/67) in infants of HBeAg(-) mothers(p<0.05).
3) Anti-HBs positive rate in infants of positive neonatal HBeAg was 77.8% (28/46) which was significantly lower than 92.1% (70/76) in infants of negative neonatal HBeAg(p<0.05).
4) Perinatal vertical transmission has occured in 2 infants of 14 anti-HBs(-) infants(14.3%). Among 8 anti-HBs(-) infants of HBeAg(+) mothers, HBsAg was perinatally transmitted in 2 infants(25%). Six anti-HBs(-) infants of HBeAg(-) mothers were not infected.
5) Among 7 anti-HBs(-) infants with positive neonatal HBeAg, 2 infants(28.6%) was perinatally infected. Seven other anti-HBs(-) infants with negative neonatal HBeAg were not infected.
6) The maximum titer of 98 anti-HBs(+) infants by passive and early active immunization was as follows; 6 infants:<10mIU/ml. 8 infants 11~100mIU/ml. 21 infants: 101~1000mIU/ml. 36 infants 1001~10000mIU/ml. 28 infants:>10000mIU/ml The anti-HBs titer was below 1000mIU/ml in 35.9% (35/98) of anti-HBs(+) infants.
In conclusion, the preventive effect of passive and early active immunization was not complete especially in HBeAg(+) infants whose mothers had HBeAg.
