Hepatitis B vaccination of neonates and children.

Perinatal transmission of the hepatitis B virus (HBV) occurs in a high percentage of infants born to mothers who are acutely infected with the virus at the time of delivery or who are chronic carriers of the hepatitis B surface antigen (HBsAg). The majority of infants who acquire the virus during the perinatal period and become HBV carriers have no clinical symptoms. However, there are reports of acute and fulminant hepatitis and even primary liver cancer occurring in a few HBsAg-positive infants. Immunoprophylaxis given to infants born to HBsAg-positive mothers at birth with a combination of hepatitis B immunoglobulin and hepatitis B vaccine is the most effective means of preventing the chronic HBV carrier state and its potential complications. In a multicenter trial in the United States, 85 to 90 percent of the children of HBsAg-positive mothers remained HBsAg-negative when treated with this combination regimen. Studies conducted outside the United States have yielded similar results. Other investigations indicate that the hepatitis B vaccine alone may be of value in preventing perinatal transmission of HBV in developing countries that are unable to afford hepatitis B immunoglobulin.