The evidence of mother to child transmission of hepatitis B virus infection in Pakistan and the need for hepatitis B immunization policy change.

OBJECTIVE To establish the hepatitis B surface antigen and hepatitis B 'e' antigen seroprevalence of mothers and their children aged 6-36 months and to assess the risk of hepatitis B transmission occurring in infants born to hepatitis B surface antigen positive mothers in Pakistan. METHODS Mothers and their children were selected from eight districts of three provinces that have been identified as high hepatitis B prevalence areas between May 2010 to February 2011. Ages of the children and their vaccination status were obtained from the lady health workers' registers and also verified from the mothers. Five ml of blood was drawn from all the children and their mothers for testing. All sera were tested for anti-hepatitis B. Those found negative were run for HBsAg the sueface antigen and those positive for it were further run for hepatitis B 'e' antigen All tests were run on Abbott machine using chemiluminesence method. EPI-info 12 was used for statistical purposes. RESULTS A total of 1561 mothers and their 1612 children were tested. Among the mothers, 590 (37.8%) were hepatitis B antibody positive. Remaining 971 (62.2%) samples were tested for surface antigen and 123 (12.7%) were found positive of which 27 (22%) showed HBeAg positivity. Out of 1612 children tested, 975 (60.5%) were positive. Remaining 637 (39.5%) were tested for surface antigen and 49 (8%) were found positive of which 24 (49%) were HBeAg positive with a perinatal hepatitis B virus transmission rate of 5.4% by 12 months of age. Of the 123 surface antigen positive mothers, 18 (14.6%) had children who were also positive, while of the 1489 children born to the 1438 surface antigen negative mothers, 31 (2.1%) were positive. Children born to surface antigen positive mothers had eight times higher risk of getting hepatitis B virus infection and the risk rose to 17 times if the mother was also HBeAg positive. Hepatitis B vaccination record showed that 1229 (76.25%) children were vaccinated at six weeks with pentavalent vaccine, but despite vaccination 33 (2.6%) became surface antigen positive. No vaccination was received by 320 (19.9%) children and out of these 16 (5%) became surface antigen positive. Moreover, the vaccinated and unvaccinated children born to surface antigen positive mothers were nine and 11 times respectively more likely to be exposed to the risk of hepatitis B virus transmission relative to vaccinated children born to surface antigen negative mothers. CONCLUSIONS Hepatitis B vaccination given at 6, 10 and 14 weeks of birth is not sufficiently protective, indicating a strong need for the introduction of birth dose into the national immunisation system.