Immunogenicity and efficacy of Russian live attenuated and US inactivated influenza vaccines used alone and in combination in nursing home residents

The immunogenicity and efficacy of Russian live attenuated and US inactivat ed trivalent influenza vaccines administered alone or in three different co mbinations were evaluated in a randomized, placebo-controlled, double-blind ed study of 614 elderly or chronically ill nursing home residents in St. Pe tersburg, Russia during the 1996-97 influenza season. Postvaccination serum antibody responses were more frequent among individuals administered the c ombination vaccines than among those vaccinated with live or inactivated va ccine alone. Only individuals who received live vaccine, alone or in combin ation with inactivated vaccine. achieved significant postvaccination increa ses in virus-specific nasal IgA. Efficacy in preventing laboratory-confirme d influenza in vaccinated versus nonvaccinated individuals was 67% (95%CI, 36-81%) for recipients of a combination of the vaccines compared with 51% ( 95%CI, -17-79%) for recipients of live vaccine alone and 50% (95%CI, -26-80 %) for recipients of inactivated vaccine alone. These results suggest that administration of a combination of influenza vaccines may provide a strateg y for improved influenza vaccination of elderly people. Published by Elsevi er Science Ltd.