Effectiveness of Influenza Vaccine in the Community-Dwelling Elderly

To provide an estimate of vaccine effectiveness, this study analyzed data from 18 cohorts of community-dwelling elderly persons during 10 influenza seasons. With 713,872 person-seasons of observation, vaccination was significantly associated with a 27% reduction in the risk of hospitalization for pneumonia or influenza and a 48% reduction in the risk of death. Most high-risk medical conditions were more prevalent among vaccinated than among unvaccinated subjects. The benefit persisted even after adjustment for possible unmeasured confounders. In community-dwelling elderly persons, influenza vaccination was significantly associated with a 27% reduction in the risk of hospitalization for pneumonia or influenza and a 48% reduction in the risk of death. Influenza continues to be a major cause of illness and death, especially among the elderly. Each year, influenza and its complications are responsible for about 186,000 excess hospitalizations for respiratory and circulatory illness 1 and 44,000 excess deaths from all causes 2 in this high-risk group. Influenza vaccines are safe and effective, and the elderly are included among the high-priority groups targeted for annual vaccination. 3 Reliable estimates of the benefits of vaccination are important for establishing informed policies regarding resource allocation for the delivery of immunizations and identifying the need for new vaccines and strategies for the prevention and control of influenza . . .