THE INFLUENCE OF SEQUENTIAL ANNUAL VACCINATION AND OF DHEA ADMINISTRATION ON THE EFFICACY OF THE IMMUNE-RESPONSE TO INFLUENZA VACCINE IN THE ELDERLY

The present study examined the effect of repeated vaccination and of d ehydroepiandrosterone (DHEA) treatment on the immune response to influ enza vaccine in elderly subjects. Seventy-one elderly volunteers, aged 61-89 years, enrolled in a prospective randomized, double-blind study to receive either DHEA (50 mg qd p.o. for 4 consecutive days starting 2 days before immunization) or placebo. Antibody response against the three strains of vaccine was measured before and 28 days after vaccin ation, and compared between previously vaccinated and non-vaccinated s ubjects. DHEA treatment did not enhance established immunity, A signif icant decrease in attainment of protective antibody titer (titer of 1: 40 or greater) against A/Texas in subjects with non-protective baselin e antibody titer was recorded following DHEA treatment compared to pla cebo (52 vs. 83%, P < 0.05). Post-immunization titers against influenz a A strains were significantly higher in those subjects who were never immunized before. Additionally, post-vaccination protective titers ag ainst the A/Johannesburg strain were more prevalent in those subjects who were never vaccinated before. The results were not the same for an ti-B/Harbin antibodies-repeated vaccination caused a non-significant i ncrease in HI titer in previously vaccinated subjects. (C) 1998 Elsevi er Science Ireland Ltd. All rights reserved.