Impact of Influenza Vaccination on Seasonal Mortality in the US Elderly Population
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- 14 February 2005
- journal article
- research article
- Published by American Medical Association (AMA) in Archives of Internal Medicine
- Vol. 165 (3), 265-272
- https://doi.org/10.1001/archinte.165.3.265
Abstract
Background Observational studies report that influenza vaccination reduces winter mortality risk from any cause by 50% among the elderly. Influenza vaccination coverage among elderly persons (≥65 years) in the United States increased from between 15% and 20% before 1980 to 65% in 2001. Unexpectedly, estimates of influenza-related mortality in this age group also increased during this period. We tried to reconcile these conflicting findings by adjusting excess mortality estimates for aging and increased circulation of influenza A(H3N2) viruses. Methods We used a cyclical regression model to generate seasonal estimates of national influenza-related mortality (excess mortality) among the elderly in both pneumonia and influenza and all-cause deaths for the 33 seasons from 1968 to 2001. We stratified the data by 5-year age group and separated seasons dominated by A(H3N2) viruses from other seasons. Results For people aged 65 to 74 years, excess mortality rates in A(H3N2)-dominated seasons fell between 1968 and the early 1980s but remained approximately constant thereafter. For persons 85 years or older, the mortality rate remained flat throughout. Excess mortality in A(H1N1) and B seasons did not change. All-cause excess mortality for persons 65 years or older never exceeded 10% of all winter deaths. Conclusions We attribute the decline in influenza-related mortality among people aged 65 to 74 years in the decade after the 1968 pandemic to the acquisition of immunity to the emerging A(H3N2) virus. We could not correlate increasing vaccination coverage after 1980 with declining mortality rates in any age group. Because fewer than 10% of all winter deaths were attributable to influenza in any season, we conclude that observational studies substantially overestimate vaccination benefit.Keywords
This publication has 16 references indexed in Scilit:
- Benefits of influenza vaccination on influenza-related mortality among elderly in the US: an unexpected findingInternational Congress Series, 2004
- Influenza Vaccination and Reduction in Hospitalizations for Cardiac Disease and Stroke among the ElderlyThe New England Journal of Medicine, 2003
- The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccinesVaccine, 2003
- Mortality Associated With Influenza and Respiratory Syncytial Virus in the United StatesJAMA, 2003
- A meta-analysis of effectiveness of influenza vaccine in persons aged 65 years and over living in the communityVaccine, 2002
- Influenza Vaccine Effectiveness in Preventing Hospitalizations and Deaths in Persons 65 Years or Older in Minnesota, New York, and Oregon: Data from 3 Health PlansThe Journal of Infectious Diseases, 2001
- Considerations for adding pneumonia and influenza vaccines to public health programmes.Vaccine, 1999
- Benefits of Influenza Vaccination for Low-, Intermediate-, and High-Risk Senior CitizensArchives of Internal Medicine, 1998
- The impact of influenza epidemics on mortality: introducing a severity index.American Journal of Public Health, 1997
- Impact of influenza epidemics on mortality in the United States from October 1972 to May 1985.American Journal of Public Health, 1987