In years when the seasonal influenza vaccine is well-matched to the circulating strain, elderly patients have a lower incidence of pneumonia and influenza (P&I) hospitalizations and mortality.
Aurora Pop-Vicas, MD, from Brown University in Providence, Rhode Island, and colleagues published the results of their retrospective cohort study online August 17 in the Journal of the American Geriatrics Society. The investigators tested the effect of vaccination in a population with uniformly high vaccination rates: more than 1 million Medicare New Hampshire nursing home residents between 2000 and 2009.
Taking advantage of the random disease variation that occurs over multiple influenza seasons, the investigators were able to compare vaccine effectiveness in the years the vaccine was well matched with vaccine effectiveness in the years it was not.
The study showed that the better the match between the influenza vaccine and the circulating strain of virus, the fewer nursing home residents were hospitalized or died.
The investigators report that average weekly all-cause mortality varied from 3.74 to 4.13 per 1000 New Hampshire residents per week. Hospitalizations for P&I varied from 2.05 to 2.43. The researchers' model estimated that a 50 percentage point increase in the A/H3N2 match rate was associated with a 2.0% reduced rate of long-stay resident deaths and a 4.2% reduced rate of P&I hospitalizations.
The authors note that these rates were similar to the pattern of P&I mortality reduction in 122 Centers for Disease Control and Prevention sentinel cities.
The study was not designed to account for the known contribution of vaccinated healthcare workers to reductions in influenza-associated disease.
The investigators designed the study to provide an answer to a frequently asked question: Does influenza vaccination help the elderly? Although annual influenza vaccination is standard care in nursing homes, some public health officials question whether the vaccination is beneficial in a frail, elderly population that tends to have poorer vaccine responsiveness.
The authors conclude from their results that influenza vaccination is an important primary prevention strategy in elderly adults. Moreover, they suggest that the effectiveness of seasonal influenza vaccines in healthier older individuals may be underestimated.
The authors have disclosed no relevant financial relationships.
J Am Geriat Soc. Published online August 17, 2015. Abstract
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Cite this: Annual Influenza Vaccinations Help the Elderly - Medscape - Aug 31, 2015.