Learning Objectives for this Presentation:
By the end of the presentation participants will be able to characterize perinatal hepatitis B cases in California.

Background:
Hepatitis B virus (HBV) may be transmitted from infected mothers to their infants. To reduce perinatal transmission, ACIP recommends that all women be tested prenatally for HBV infection and all infants be given HBV vaccine within 12 hours of birth. Infants born to infected mothers should receive hepatitis B immune globulin, complete the vaccine series and be tested for immunity.

Objectives:
To characterize perinatal HBV cases in California.

Methods:
We examined perinatal HBV case report data for infants born January 1, 2000 through December 31, 2005 and case management data of infants enrolled in the California Perinatal Hepatitis B Prevention Program (CA PHPP).

Results:
198 of 8,639 (2.3%) infants born in California during the study period who had post-vaccination serologic testing (PVST) for HBV immunity were found to be HBV-infected. Most (88%) had been treated appropriately; 24 (12.1%) were administered a late dose of HBV vaccine, 3 (1.5%) were not administered HBIG, and 1 did not receive the 3rd dose of HBV vaccine.
Exposed infants enrolled in the CA PHPP who had PVST were more likely to be infected with HBV if they were born to a mother who was Vietnamese (OR 2.9) or Hmong (OR 2.3) and less likely to be infected if born to a Chinese mother (OR 0.78).

Conclusions:
Appropriate clinical management prevents most but not all cases of perinatal HBV infection. Certain ethnic groups may be at higher risk for perinatal HBV transmission. It is unclear whether women in ethnic groups associated with an increased risk of transmission have higher viral load, viral mutations or other biological explanations for the failure of infant post-exposure prophylaxis. Prenatal antiviral treatment may be warranted in selected women.