title: Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomised controlled trial.
abstract: BACKGROUND
  Vaccination of health-care workers has been claimed to prevent nosocomial influenza infection of elderly patients in long-term care. Data are, however, limited on this strategy. We aimed to find out whether vaccination of health-care workers lowers mortality and the frequency of virologically proven influenza in such patients.
  
  
  METHODS
  In a parallel-group study, health-care workers in 20 long-term elderly-care hospitals (range 44-105 patients) were randomly offered or not offered influenza vaccine (cluster randomisation, stratified for policy for vaccination of patients and hospital size). All deaths among patients were recorded over 6 months in the winter of 1996-97. We selected a random sample of 50% of patients for virological surveillance for influenza, with combined nasal and throat swabs taken every 2 weeks during the epidemic period. Swabs were tested by tissue culture and PCR for influenza viruses A and B.
  
  
  RESULTS
  Influenza vaccine uptake in health-care workers was 50.9% in hospitals in which they were routinely offered vaccine, compared with 4.9% in those in which they were not. The uncorrected rate of mortality in patients was 102 (13.6%) of 749 in vaccine hospitals compared with 154 (22.4%) of 688 in no-vaccine hospitals (odds ratio 0.58 [95% CI 0.40-0.84], p=0.014). The two groups did not differ for proportions of patients positive for influenza infection (5.4% and 6.7%, respectively); at necropsy, PCR was positive in none of 17 patients from vaccine hospitals and six (20%) of 30 from no-vaccine hospitals (p=0.055).
  
  
  CONCLUSIONS
  Vaccination of health-care workers was associated with a substantial decrease in mortality among patients. However, virological surveillance showed no associated decrease in non-fatal influenza infection in patients.
authors.affiliation: Institute of Virology, University of Glasgow, UK.
authors.forename: W F
authors.initials: WF
authors.lastname: Carman
authors.forename: A G
authors.initials: AG
authors.lastname: Elder
authors.forename: L A
authors.initials: LA
authors.lastname: Wallace
authors.forename: K
authors.initials: K
authors.lastname: McAulay
authors.forename: A
authors.initials: A
authors.lastname: Walker
authors.forename: G D
authors.initials: GD
authors.lastname: Murray
authors.forename: D J
authors.initials: DJ
authors.lastname: Stott
mesh_terms: D000368:Aged; D006282:Health Personnel; D006707:Homes for the Aged; D006801:Humans; D017053:Infection Control / Q000379:methods*; D017757:Infectious Disease Transmission, Professional-to-Patient / Q000517:prevention & control; D007251:Influenza, Human / Q000401:mortality* / Q000517:prevention & control*; D008134:Long-Term Care; D016133:Polymerase Chain Reaction; D012606:Scotland; D014611:Vaccination / Q000706:statistics & numerical data*; D000078329:Workforce