A prospective study of 18 infants of chronic HBsAg mothers.

28 of 1002 pregnant Sicilian women (2.8%) were asymptomatic HBsAg chronic carriers. 18 children of these women were followed and at least 15 of them showed evidence of transplacental infection with HBsAg, resulting either from the presence of the antigen in cord blood, or from the development of the corresponding antibody in the serum within the first 2 months of life. Despite this, only 2 or 3 of the infants developed chronic antigenaemia from age 2--4 months. Only the infants whose mothers were HBeAb-negative, and who themselves remained HBsAb-negative during the first months of life, became HBsAg carriers. On the basis of these results, a strategy is suggested for selecting infants from areas with a high prevalence of HBsAg carriers so that they can be given passive immunisation with hyperimmune globulin.