The hepatitis B immunization programme in Singapore.

A voluntary immunization programme to prevent perinatal transmission of hepatitis B virus (HBV) infection in Singapore was implemented on 1 October 1985 as an integral component of the national childhood immunization programme. Up to April 1988, a total of 68,845 mothers who attended government maternal and child health clinics were screened for the disease. Of these, 2432 (3.5%) were positive for hepatitis B surface antigen (HBsAg) and 904 (1.3%) for hepatitis B e antigen (HBeAg). Virtually all the babies born to carrier mothers completed the full immunization schedule; and in addition, those of HBeAg-positive mothers were given a dose of hepatitis B immunoglobulin at birth. The hepatitis B immunization programme was extended on 1 September 1987 to cover all newborns. About 90% of the 15,943 babies delivered in government institutions from September 1987 to April 1988 were immunized at birth, with the subsequent doses being administered at maternal and child health clinics at 4-6 weeks and 5 months later. More than 85% of the children given the full course of plasma-derived and yeast-derived hepatitis B vaccine from birth continued to have protective antibody to HBV two years after immunization. The programme is being closely monitored to assess the duration of immunity and the need for booster doses, while seronegative adults are also being encouraged to be vaccinated.