Home and Community Care Digest

Home and Community Care Digest June 2005 : 0-0

Annual revaccination programs benefit the elderly

Abstract

The effects of influenza have become increasingly harmful to elderly individuals, particularly those with chronic conditions. There have been conflicting reports as to the effectiveness of vaccination programs for the elderly. This study examines the association between annual revaccination for influenza and the risk of mortality among community-dwelling elderly individuals. It was ascertained that with revaccination, there was a reduction in the risk of mortality. This study is useful in to direct policy initiatives for annual vaccination influenza programs for the general Canadian population, particularly for those at high-risk.
Background: The negative consequences of contracting influenza increases with age as well as for those with chronic illnesses. As a result, there has been a strong incentive to implement influenza vaccination programs for these high-risk individuals, particularly the elderly population. To date, clinical studies have reported mixed results in the effectiveness of vaccinating high-risk populations. However, no studies have investigated the benefits of annual revaccination programs to protect the elderly against influenzaassociated morbidity and mortality. The objective of this study is to examine the effect of annual influenza revaccination programs on the mortality of elderly individuals residing in the community.

Methods: This study assessed 26,071 community-dwelling individuals, aged 65 years and older, living in the Netherlands, from 1996 through 2002. The association between the number of consecutive influenza vaccinations and mortality was determined, controlling for age, sex, chronic respiratory and cardiovascular disease, hypertension, diabetes, renal failure and cancer. Influenza vaccinations were recorded once the participant entered the study but any vaccinations prior to the study were not analyzed.

Results: 3,485 individuals died during the study period and it was estimated that the influenza vaccination prevented one death for every 302 vaccination. In the total population, any influenza vaccination is associated with a 22% decreased risk in mortality. In comparison to the first vaccination, which has no significant association to mortality, revaccination is associated with a significant decrease in mortality risk by 24%. In an epidemic period, defined by an increase in the prevalence of influenza, revaccination is associated with a decrease in mortality by 28%. Increasing age was also an important factor in the effectiveness of revaccination, as those aged 65-69 did not experience a reduction in mortality after revaccination, while those aged 70 and over had more than a 22% reduction in mortality. Finally, the authors investigated the possibility that those who had not been vaccinated may have been sicker than those who were but found no association between the two groups.

Conclusion: It is observed that revaccination is associated with a decrease in mortality amongst community-dwelling elderly individuals. Given that influenza associated mortality and morbidity increases with age and illness, it is important to investigate the effects of influenza prevention programs. The implications of this study may suggest policy directives to further develop effective influenza programs for the elderly in Canada.

Reference: Voordouw, A., Sturkenboom, M. Dieleman, J., Stijnen, T., Smith, D., van der Lei, J., Stricker, B. 2004. "Annual Revaccination Against Influenza and Mortality Risk in Community Dwelling Elderly Persons". JAMA. 292(17): 2089-2095

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