Antibody response to 1995-1996 influenza vaccine in institutionalized and non-institutionalized elderly women

Background: Concern about poor responsiveness to influenza vaccination by institutionalized elderly people. Objective: To determine whether institutionalized elderly volunteers develop a significant antibody response following influenza vaccine and to compare this response with that of non-institutionalized subjects. Methods: The haemagglutination-inhibiting antibody response after 1995-1996 influenza vaccination [A/Shangdong/9/93 (H3N2), A/Taiwan/1/86 (H1N1), B/Panama/45/90] was estimated in 80 elderly women living in a nursing home and com pa red with that of 51 non-institutionalized women. Results: No differences were found in the prevaccination status, and, after vaccination, a significant humoral response was elicited both in institutionalized and noninstitutionalized elderly subjects against all th ree influenza strains tested. The immune response of institutionalized patients was satisfactory and significantly higher than that observed in non-institutionalized women. These results were confirmed both by a separate analysis of homogeneous subgroups stratified according to the presence in the two cohorts of potential causes of differential antibody response (prevaccination antibody titre, age, long-term drug treatment, risk factors for influenza infection, and physical disability) and by logistic regression analysis in order to adjust immune responses for the different variables. Conclusion: Influenza vaccination is effective in elderly people living in nursing homes. However, the postvaccination antibody response to influenza vaccine is influenced by different factors directly or indirectly related to residence.