Perinatal hepatitis B transmission in a northern California county after implementation of a case management program

Background: Without appropriate immunoprophylaxis 70 to 90% of infants born to hepatitis B surface antigen (HBsAg)-positive mothers become infected with hepatitis B virus (HBV). Timely administration of immunoprophylaxis is almost 90% effective in preventing perinatal infection. Methods: Women of reproductive age reported in 2008 to San Mateo County as being HBsAg-positive were contacted to determine pregnancy status. Pregnant women were enrolled in our Perinatal Hepatitis B Prevention Program and offered intensive case management. HBV-exposed infants born in 2008, including those born to women identified in 2007 and those identified after delivery, were closely followed. Basic demographic data, immunoprophylaxis rates and post-vaccination serology (PVS) testing results were obtained. Results: 78 HBsAg-positive pregnant women were identified. 89 % of women were Asian Pacific Islanders (APIs). 49% were Chinese, 26% Filipino, and 14% other API. 4% were of Turkish, Middle Eastern, and Armenian descent. 1% was of mixed race, with race remaining unknown in 6% of cases. 56 HBsAg-exposed infants were born in 2008. Within 12 hours of birth, 89% of the infants received Hepatitis B Immune Globulin (HBIG) and 96% received the first HBV vaccine dose. To date, all eligible infants have completed the full vaccination series. 75 % of eligible infants have undergone PVS testing and are HBV-immune. Conclusions: Perinatal HBV transmission rates can be minimized with intensive case management. Additional resources are needed to refer HbsAg-positive pregnant women for treatment evaluation and to offer screening/immunization to their household and sexual contacts.