Prevention of hepatitis B virus carrier state in infants according to maternal serum levels of HBV DNA.

235 infants of HBeAg-carrier mothers in Hong Kong were assigned to four study groups. Groups I, II, and III received hepatitis-B (HB) vaccine at birth and at 1, 2, and 6 months. Group I also received seven monthly injections of HB immunoglobulin (HBIg), and group II received one HBIg injection at birth. Group III received vaccine only and group IV received placebo for both vaccine and HBIg. At the age of 3 years, all infants of the three treatment groups were significantly protected against the HB virus (HBV) carrier state compared with the placebo group (p less than 0.0001); the protective efficacy rates in groups I, II, and III were 87%, 80%, and 65%, respectively. At all times, group I was significantly better protected than group III. In groups III and IV, infants of mothers with serum HBV DNA levels of 5 pg/ml or above were at a significantly higher risk of acquiring the HBV carrier state than those whose mothers had HBV DNA levels below 5 pg/ml. This difference was not significant in groups given HBIg. Of the 183 infants who initially escaped HBV infection, 73 (40%) had transient and 8 (4%) chronic HBV infection between 6 and 36 months. Vaccinated infants who had actively formed anti-HBs remained well protected against the HBV carrier state. However, infants in groups I and II with no active anti-HBs response to vaccine became at risk for the HBV carrier state when the passively acquired anti-HBs antibodies had disappeared. HBIg should be included in HB vaccination schedules for all infants of HBeAg-positive mothers.