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Effect of Influenza Vaccination of Nursing Home Staff on Mortality of Residents: A Cluster-Randomized Trial

Authors


Address correspondence to Fabrice Carrat, Epidémiologie, systèmes d'information, modélisation, UMR-S 707, Faculté de médecine Saint Antoine, 27, rue Chaligny, 75571 Paris cedex 12, France.E-mail: carrat@u707.jussieu.fr

Abstract

OBJECTIVES: To evaluate the effect of staff influenza vaccination on all-cause mortality in nursing home residents.

DESIGN: Pair-matched cluster-randomized trial.

SETTING: Forty nursing homes matched for size, staff vaccination coverage during the previous season, and resident disability index.

PARTICIPANTS: All persons aged 60 and older residing in the nursing homes.

INTERVENTION: Influenza vaccine was administered to volunteer staff after a face-to-face interview. No intervention took place in control nursing homes.

MEASUREMENTS: The primary endpoint was total mortality rate in residents from 2 weeks before to 2 weeks after the influenza epidemic in the community. Secondary endpoints were rates of hospitalization and influenza-like illness (ILI) in residents and sick leave from work in staff.

RESULTS: Staff influenza vaccination rates were 69.9% in the vaccination arm versus 31.8% in the control arm. Primary unadjusted analysis did not show significantly lower mortality in residents in the vaccination arm (odds ratio=0.86, P=.08), although multivariate-adjusted analysis showed 20% lower mortality (P=.02), and a strong correlation was observed between staff vaccination coverage and all-cause mortality in residents (correlation coefficient=−0.42, P=.007). In the vaccination arm, significantly lower resident hospitalization rates were not observed, but ILI in residents was 31% lower (P=.007), and sick leave from work in staff was 42% lower (P=.03).

CONCLUSION: These results support influenza vaccination of staff caring for institutionalized elderly people.

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