Antibody response to postexposure prophylaxis in infants born to hepatitis B surface antigen-positive women

Background.

Annually 20 000 infants are born to hepatitis B surface antigen (HBsAg)-positive US women. Without prophylaxis 30% risk chronic hepatitis B virus infection, and 25% of those risk dying from resulting liver cirrhosis or liver cancer as adults.

Methods.

We attempted to interview each HBsAg-positive pregnant woman reported to the health department between 1992 and 1997, to provide their infants with immunoprophylaxis at birth and in the clinic or home and to serotest at 9 to 15 months of age.

Results.

Of 879 women reported, 92% enrolled; 787 delivered 796 live infants; 91% of infants received hepatitis B immunoglobulin; 98, 95 and 89% received hepatitis B vaccine (HepB) Doses 1, 2 and 3, respectively; and 80% were serotested. Of these 2.2% were HBsAg-positive and 97% had antibody to HBsAg (anti-HBs) of ≥10 mIU/ml. Anti-HBs concentrations measured in 504 infants were 10 to 99 mIU/ml (25%), 100 to 999 mIU/ml (43%) and ≥1000 mIU/ml (29%). Serotesting was less likely among infants of mothers <20 years of age [odds ratio (OR) 2.5]; white, non-Hispanic (OR 2.8); or with a household income of <$15 000/year (OR 2.0). Lower antibody titers were found when serotesting at 4 to 12 months than at <4 months after HepB-3 (OR 1.8 to 4.4), with HepB-3 receipt <6 months after HepB-2 (OR 2.5) and when household income was <$15 000/year (OR 2.1).

Conclusions.

Centralized case management with home visits resulted in high rates of complete immunoprophylaxis and postvaccination testing among infants born to HBsAg-positive women. Perinatal immunoprophylaxis was immunogenic under routine public health use, with higher anti-HBs titers occurring in infants tested <4 months postvaccination. Because infants in households with low income had higher rates of nonprotective antibody responses, they may benefit from extra efforts to ensure that serotesting is conducted postvaccination.