IMMUNOGENICITY OF AN INACTIVATED HEPATITIS-A VACCINE IN ALASKA NATIVE CHILDREN AND NATIVE AND NONNATIVE ADULTS

The response to an inactivated hepatitis A vaccine was assessed in 307 persons: 163 Alaska Native children, ages 3-6 years, and 144 Native (84) and non-Native (60) adults. All adults received the same vaccine schedule (0, 1, and 12 months), whereas children were randomized to receive three different schedules (0, 1, and 6; 0, 1, and 2; or 0, 1, and 12 months). After one dose, 141 (96%) of 147 children and 129 (90%) of 143 adults responded with levels of antibody to hepatitis A virus >20 mIU/mL. After three doses, all participants responded. The geometric mean titer (GMT) 1 month after the third dose was significantly higher in children who received the third dose 12 months after the first dose rather than 2 months after the first dose. While there were differences in the GMT of some blood samples by age, sex, and ethnicity, all participants responded to the vaccine.