Failed postnatal immunoprophylaxis for hepatitis B: Characteristics of maternal hepatitis B virus as risk factors

A retrospective case-control study was conducted to determine why some infants born full-term without obstetric intervention to hepatitis B e antigen (HBeAg)-seropositive mothers become infected by hepatitis B virus (HBV) despite having received passive-active immunoprophylaxis. Cases and controls comprised 12 hepatitis B surface antigen (HBsAg)-seropositive infants and 22 HBsAg-seronegative infants, respectively. Infants infected by putative vaccine-escape mutants were excluded. Risk factors, after adjustment for the level of maternal viremia, were the following allelic base changes in maternal HBV: C-158, A(328), G(365), and A(479) (P = .017, .005, .003, and .005, respectively). High-level maternal viremia (i.e., greater than or equal to 10(8) genome equivalents/mL) was a significant factor only after adjustment for G(365) (P = .027). HBV DNA sequences recovered from one of the cases, the case's mother, and three infected contacts all had the high-risk mutations. Specific allelic mutations in maternal HBV and level of maternal viremia are potential predictors of vertical breakthrough infection.