84. Vaccinating the Nursing Home Population for Seasonal Influenza Reduces Morbidity and Mortality
Session: Oral Abstract Session: Influenza Vaccine - Clinical Impact and Vaccine Response
Thursday, October 3, 2013: 9:45 AM
Room: The Moscone Center: 200-212
Background:  Seasonal influenza costs an estimated $87 billion annually.  Elderly people incur most of the disease burden, and morbidity and mortality are disproportionately greatest among nursing-home (NH) residents. Recent studies have questioned the effectiveness of influenza vaccine, the cornerstone of prevention, for the older adult. Using a novel regression model that accounts for the annual and regional variation in the prevailing influenza strain and vaccine match, we estimated the impact of vaccination on hospitalizations and mortality on the NH population over a 9-year span.

Methods:   We merged Medicare enrollment, inpatient and skilled nursing facility claims with NH assessments for all Medicare fee-for-service residents in US nursing-homes located in the 122 CDC surveillance cities from 2000 to 2009. We created a residential history file of long stay residents and facility weekly aggregates of the following outcomes: hospitalizations due to pneumonia and influenza (P&I), and all-cause mortality among NH residents, and city-level P&I mortality, as reported by the CDC. We calculated the seasonal vaccine match rate (our explanatory variable) as the proportion of regionally circulating strains antigenically typed by the CDC that were identical to the vaccine strains used in that season. We estimated the relationship between the above outcomes and the match rates for H3N2 and B, the two influenza strains associated with most of the clinically relevant disease in the elderly, using a facility fixed effects multivariate regression model.

Results: We found that P&I hospitalizations and all-cause deaths among NH residents vary considerably with the match rate between the vaccine and regionally circulating strains, as does city-level P&I mortality.  For the long-term stay NH population, our model estimates a 4.5% reduction in all-cause mortality and a 7.7% reduction in P&I hospitalizations in a year with excellent (> 75%) match versus a year with poor (≤ 25%) match. We found the association between vaccine match and reduction in P&I hospitalizations to be strongest for the H3N2 strain.   

Conclusion:  Influenza vaccine prevents P&I hospitalizations and mortality in the nursing-home population.

Aurora Pop-Vicas, MD, MPH1,2, Momotazur Rahman, PhD3, Pedro Gozalo, PhD3, Stefan Gravenstein, MD, MPH3,4 and Vincent Mor, PhD5,6, (1)Medicine, Memorial Hospital of Rhode Island, Pawtucket, RI, (2)Medicine, Infectious Diseases, Alpert Medical School At Brown University, Providence, RI, (3)Center for Gerontology and Healthcare Research, Brown University, Providence, RI, (4)Medicine, Geriatrics, Case Western Reserve University, Cleveland, OH, (5)Brown University School of Public Health, Department of Health Services, Policy & Practice, Providence, RI, (6)Veterans Medical Center, Providence, RI


A. Pop-Vicas, None

M. Rahman, None

P. Gozalo, None

S. Gravenstein, None

V. Mor, None

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