Hepatitis B immunisation coverage of infants born to chronic carrier mothers in Victoria

Abstract

Infants born to HBsAg- (hepatitis B surface antigen) carrier mothers are highly likely to become chronic hepatitis B (HB) carriers themselves unless their status is recognised at birth and they are immunised with three doses of HB vaccine, the first within 48 hours of birth, concurrent with hepatitis B immune globulin (HBIG). This study was designed to determine how many infants born in Victoria to carrier mothers completed three doses of HB vaccine. We sent the names of all infants of HBsAg-carrier mothers notified in Victoria between 1.7.91 and 30.6.92 to the appropriate local government immunisation providers and requested information on how many doses of HB vaccine, DTP (diphtheria-tetanus-pertussis) or CDT (combined diphtheria-tetanus), and OPV (oral polio vaccine) they had received. The HBsAg-carrier prevalence of women giving birth in Victoria in 1991-92 was at least 0.52%. Of the 336 infants notified, 239 (71.1%) were recorded in local government records. Of these 239, 90.8% received at least two doses and 80.8% received at least three doses of hepatitis B vaccine. There was no significant difference in the number who received three doses of HB vaccine compared with three doses of DTP or CDT vaccine. Of the entire cohort of 336, only 57.4% were documented as being completely immunised against hepatitis B. HB immunisation coverage for these infants needs to be improved. The high rate of loss to follow-up, especially between the maternity hospital and the community, is disturbing. Mechanisms for intensive prospective follow-up of these infants should be developed to prevent loss to follow-up and to encourage full immunisation against HB. Improving HB immunisation coverage of infants in high HBsAg-prevalence ethnic groups and introduction of universal infant HB immunisation may lead to increased coverage of infants of carriers by serving as back-up mechanisms for those lost to follow-up.