Development and persistence of antibody in a high risk institutionalized population given plasma-derived hepatitis B vaccine

Abstract Three hundred and twenty-two (322) persons with severe mental handicaps were given plasma-derived hepatitis B vaccine (20 μg dose at 0, 1 and 6 months). Following the third injection, 95% of the vaccinees were positive for anti-HBs, while 92% achieved a protective level of antibody (⩾ 10 mIU ml −1 ) with a geometric mean titre of 2568 mlU ml −1 . Females responded better than males. Antibody responses declined with increasing age in both sexes, but they were not significantly influenced by body weight. Persistence of antibody in responders was followed over 4 years. The proportion of responders maintaining ⩾ 10 mIU ml −1 was a function of initial antibody titre but was not significantly affected by sex, age or body weight. Overall, 76% of the responders are estimated to have ⩾ 10 mIU ml −1 of anti-HBs 4 years after the first injection of vaccine.