Passive immunoprophylaxis of hepatitis B virus infections in newborn infants.

Newborn infants of mothers who were chronic carriers of hepatitis Bs antigen (HBsAg) were randomly allocated to be treated or not treated with hyperimmune hepatitis B immunoglobulin (HBIg) at birth and six weeks and were then followed up to one year with sequential blood tests. Ninety percent of all untreated infants born of mothers positive for both HBsAg and hepatitis Be antigen became chronic carriers of HBsAg at one year. In contrast only 9% of infants treated with HBIg became HBsAg positive. Mothers who were HBsAg positive but hepatitis Be antigen negative only uncommonly infected their infants, with 6% being HBsAg positive at one year. Nearly all infections were in Pacific Islanders, Maoris or Asians. It is recommended that antenatal testing of these groups most at risk for hepatitis B virus spread, be initiated, followed by passive immunoprophylaxis with HBIg of infants born of HBsAg, HBeAg positive mothers.