Beginning in 1982 all pregnant women undergoing prenatal routine blood analysis in three large city hospitals and one large rural area were tested for hepatitis B surface antigen (HBsAg). Infants of all HBsAg-positive mothers received hepatitis B immunoglobulin (HBIg), 0.5 mL/kg of body weight within two hours of birth and, after randomization, 10 µg of hepatitis B vaccine either at 0, 1, 2, and 11 months of age (schedule A) or at 3, 4, 5, and 11 months of age (schedule B). A second injection of HBIg (1 mL) was given to infants on schedule B at 3 months of age. Blood samples were obtained at 3, 6, 11, 12, 24, and 36 months. In a two-year period, 28,412 pregnant women were tested for HBsAg; screening efficiency varied between 85% and 98%. The overall prevalence of HBsAg was 0.8%, with a marked variation between urban centers (2.2%) and the rural area (0.3%). Vaccinations were received by 180 of 193 infants of HBsAg-positive mothers (90 on schedule A and 90 on schedule B). Concentrations of hepatitis B surface antibody less than 10 IU/L were observed in nine instances in five children from group A and in seven instances in six children from group B. Four hepatitis B viral infections (two HBsAg carriers, two who underwent antihepatitis B core seroconversions) were recorded in group A v one infection (antihepatitis B core seroconversion) in group B. The protective efficacy of the program (screening plus passive immunization and delayed vaccination) was 94%. The estimated cost of preventing one case of hepatitis B infection in neonates was $3,000 (US currency). It is concluded that screening all pregnant women for HBsAg can be introduced effectively at reasonable costs in a country with a low prevalence of HBsAg and a high proportion of home deliveries. Delayed active vaccination starting at 3 months of age may be an effective and, for reasons of high compliance and low cost, attractive alternative to early active vaccination.
Seroprevalence of Hepatitis B Surface Antigen among Pregnant Women Attending Antenatal Clinic in Federal Medical Center Keffi, Nigeria
