title: Flu: effect of vaccine in elderly care home residents: a randomized trial.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  A two-arm, partially blind, randomized, multicenter, parallel-group, controlled trial.
  
  
  METHODS
  Twenty-six care homes in three South London boroughs in fall 2004.
  
  
  METHODS
  Two hundred seventy-seven elderly permanent care home residents meeting eligibility criteria.
  
  
  METHODS
  Postvaccination blood samples were randomized to booster evaluation or no booster evaluation (control). If evaluation revealed inadequate seroprotection, a booster vaccine was administered.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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 uncertain.
authors: Institute of Psychiatry, King's College London, London, United Kingdom. fiona.gaughran@iop.kcl.ac.uk
authors: Fiona
authors: F
authors: Gaughran
authors: Rebecca
authors: R
authors: Walwyn
authors: Rob
authors: R
authors: Lambkin-Williams
authors: Paul
authors: P
authors: Whelan
authors: Katherine
authors: K
authors: Chatterton
authors: John
authors: J
authors: Oxford
authors: Alastair
authors: A
authors: Macdonald
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D005260:Female; D006707:Homes for the Aged; D006801:Humans; D017589:Immunization Programs; D007117:Immunization, Secondary; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000401:mortality / Q000517:prevention & control*; D008131:London / Q000453:epidemiology; D008297:Male; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D007252:Influenza Vaccines