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Flu: Effect of Vaccine in Elderly Care Home Residents: A Randomized Trial
Author(s) -
Gaughran Fiona,
Walwyn Rebecca,
LambkinWilliams Rob,
Whelan Paul,
Chatterton Katherine,
Oxford John,
Macdonald Alastair
Publication year - 2007
Publication title -
journal of the american geriatrics society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.992
H-Index - 232
eISSN - 1532-5415
pISSN - 0002-8614
DOI - 10.1111/j.1532-5415.2007.01471.x
Subject(s) - medicine , booster (rocketry) , booster dose , vaccination , influenza vaccine , randomized controlled trial , confidence interval , odds ratio , pediatrics , titer , immunology , antibody , physics , astronomy
OBJECTIVES: To determine whether assessing seroprotection after influenza vaccine and administering booster vaccination where not achieved reduces hospitalization and death. To estimate the overall seroprotection rate of influenza vaccine. DESIGN: A two‐arm, partially blind, randomized, multicenter, parallel‐group, controlled trial. SETTING: Twenty‐six care homes in three South London boroughs in fall 2004. PARTICIPANTS: Two hundred seventy‐seven elderly permanent care home residents meeting eligibility criteria. INTERVENTION: Postvaccination blood samples were randomized to booster evaluation or no booster evaluation (control). If evaluation revealed inadequate seroprotection, a booster vaccine was administered. MEASUREMENTS: Primary outcome was hospitalization to end April 2005; secondary outcomes were death, antibiotic use, and seroprotection. RESULTS: Sixty percent of the controls and 41% of the booster evaluation group responded to routine vaccination. Booster vaccination where indicated increased seroprotection rates in the booster evaluation group to 66%. Treatment groups did not differ in any outcome measures in the intention‐to‐treat analysis (hospitalization odds ratio=1.02, 95% confidence interval=0.55–1.87). There was a tendency towards greater differences between groups in the per‐protocol analysis than in the intention‐to‐treat analysis, particularly regarding seroprotection rates. The same effect was observed in the a priori exploratory analysis of residents not seroprotected after routine vaccination alone. CONCLUSION: In a year without circulating influenza, there is no clinical benefit of administering a booster vaccine if routine trivalent vaccination fails to result in seroprotection. Hemagglutination titers rose in two strains postbooster vaccination but fell against the novel strain, Wyoming. The benefit of such a booster strategy when influenza is prevalent thus remains unc ertain.