Mother-to-infant transmission of hepatitis B is more common among mothers positive for hepatitis B e antigen (HBeAg). Intrauterine infection, in which the infant is seropositive for hepatitis B surface antigen (HBsAg), remains a significant problem in the elimination of vertical hepatitis B transmission. Tang and associates examined the prevalence of HBsAg among infants born to HBeAg–positive, HBsAg–carrier mothers in Taiwan and the outcome of immunoprophylaxis in these infants.
The study included 665 infants born to HBeAg–positive, HBsAg–carrier mothers. Hepatitis B status was determined at birth and during long-term follow-up. All of the infants received hepatitis B immune globulin (HBIG) within 24 hours of birth and three or four subsequent doses of hepatitis B vaccine.
Sixteen (2.4 percent) of the 665 infants were seropositive for HBsAg within one hour of birth. All 16 infants remained HBsAg positive during the first six months of life. Follow-up in 12 of the 16 infants continued for 33 months to 12 years (mean follow-up: 8.1 years). In all but one child, the HBsAg–positive state (carrier state) persisted throughout the follow-up period. The child who showed seroconversion to hepatitis B surface antibody (anti-HBs) did so at four years of age. None of the children had abnormal serum alpha-feto-protein levels, or symptoms or signs of chronic liver disease.
The authors conclude that the current immunoprophylaxis strategy, including administration of HBIG within 24 hours after birth plus three or four doses of hepatitis B vaccine, fails to prevent chronic infection in infants who become infected in utero. The authors speculate that infants exposed to HBeAg and other hepatitis B antigens in utero may be more tolerant to the various antigens, including HBsAg, and unresponsive to hepatitis B vaccine. When immune tolerance wanes, seroconversion may occur.