Abstract
This serial cohort study assessed the risk of hospitalization or death associated with influenza and the effectiveness of influenza vaccination among subgroups of elderly members of 3 managed-care organizations in the United States. Data on baseline characteristics and outcomes were obtained from computerized databases. A total of 122,974 (1996-1997 season) and 158,454 (1997-1998 season) persons were included in the cohorts. Among unvaccinated persons, hospitalizations for pneumonia/influenza or death occurred in 8.2 of 1000 healthy and 38.4 of 1000 high-risk persons in year 1, and in 8.2 of 1000 healthy and 29.3 of 1000 high-risk persons in year 2. After adjustments, vaccination was associated with a 48% reduction in the incidence of hospitalization or death (95% confidence interval [CI], 42-52) in year 1 and 31% (95% CI, 26-37) in year 2. Effectiveness estimates were statistically significant and generally consistent across the healthy and high-risk subgroups. The absolute risk reduction, however, was 2.4- to 4.7-fold higher among high-risk than among healthy elderly persons. All elderly individuals may substantially benefit from vaccination. However, the impact of influenza is greater in persons with high-risk medical conditions.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 370-377 |
| Number of pages | 8 |
| Journal | Clinical Infectious Diseases |
| Volume | 35 |
| Issue number | 4 |
| DOIs | |
| State | Published - Aug 15 2002 |
Bibliographical note
Funding Information:Financial support: This project was funded and sponsored by the National Vaccine Program Office and the Centers for Disease Control and Prevention through an agreement with the American Association of Health Plans. E.H.’s participation was supported by a grant from the Dutch Asthma Foundation, Leusden, The Netherlands.
