Evaluation of screening for hepatitis B surface antigen during pregnancy in a population with a high prevalence of hepatitis B surface antigen-positive/hepatitis B e antigen-negative carriers.

Background: Universal hepatitis B vaccination in infancy was implemented in Israel in 1992. The program consists of active vaccination at birth and at 1 and 6 months of age, without hepatitis B surface antigen (HBsAg) screening during pregnancy. Infants of HBsAg carrier mothers do not receive specific hepatitis B immunoglobulin in addition to vaccine at birth. The recently arrived Jewish immigrants from Ethiopia are the group with the highest rate of HBsAg carriage (approximately 10%) in Israel.

Aim: The objective of this study was to evaluate whether the present policy is effective against perinatal HBV transmission from mothers of Ethiopian origin to their infants.

Methods: The study group included 411 Israeli born children, offspring of mothers of Ethiopian origin. All infants were fully vaccinated starting at birth. Sera were collected from the children at the age of 9 to 36 months and from their mothers. Tests for HBsAg, antibodies to HBsAg (anti-HBs) and antibodies to hepatitis B core antigen (anti-HBc) were performed.

Results: Eighty-nine percent of the children had detectable anti-HBs, including 82.2% with protective anti-HBs concentrations (> or =10 mIU/ ml). Although 24 mothers (6.2%) were HBsAg carriers, none of the children was HBsAg-positive. Seven of 394 infants (1.7%) tested positive for anti-HBc. This test became negative in 5 of 6 who were followed for 12 months. The percentage of infants with protective anti-HBs concentrations decreased significantly from 91.4% at 9 to 12 months to 70.1% at 31 to 36 months of age. The mother's infection status was not associated with the infant's response to vaccine. Calculation based on the above data suggests that screening for HBsAg in pregnancy in that group is not cost-effective.

Conclusions: Our results suggest that the Israeli vaccination program against HBV infection is effective, even in a high risk population, and additional measures are not cost-effective.