The Perinatal Hepatitis B Prevention Program (PHBPP) is a surveillance and reminder program for infants and household contacts of pregnant women who are HBsAg positive. The main goal of the PHBPP is to reduce the incidence of hepatitis B in infants born to women with hepatitis B virus infection. A follow-up system is in place to help assure that infants born to HBsAg-positive women receive appropriate post-exposure prophylaxis. Infants born to HBsAg-positive women are screened for HBsAg (to see if they have hepatitis B) and anti-HBs (to see if they have adequate antibody [are protected] against hepatitis B). This follow-up testing is done at 9-15 months of age. Additionally, all household and sexual contacts of pregnant women with hepatitis B are identified, tested, and susceptible contacts are offered the 3-dose series of hepatitis B vaccine.