title: Effectiveness of influenza vaccination in working-age adults with diabetes: a population-based cohort study.
abstract: BACKGROUND
  Guidelines recommend influenza vaccinations in all diabetic adults, but there is limited evidence to support vaccinating working-age adults (<65 years) with diabetes. We examined the effectiveness of influenza vaccine in this subgroup, compared with elderly adults (≥ 65 years) for whom vaccination recommendations are well accepted.
  
  
  METHODS
  We identified all adults with diabetes, along with a sample of age-matched and sex-matched comparison subjects without diabetes, from 2000 to 2008, using administrative data from Manitoba, Canada. With multivariable Poisson regression, we estimated vaccine effectiveness (VE) on influenza-like illnesses (ILIs), pneumonia and influenza (PI) hospitalisations and all-cause (ALL) hospitalisations during periods of known circulating influenza. Analyses were replicated outside of influenza season to rule out residual confounding.
  
  
  RESULTS
  We included 543 367 person-years of follow-up, during which 223 920 ILI, 5422 PI and 94 988 ALL occurred. The majority (58%) of adults with diabetes were working age. In this group, influenza vaccination was associated with relative reductions in PI (43%, 95% CI 28% to 54%) and ALL (28%, 95% CI 24% to 32%) but not ILI (-1%, 95% CI -3% to 1%). VE was similar in elderly adults for ALL (33-34%) and PI (45-55%), although not ILI (12-13%). However, similar estimates of effectiveness were also observed for all three groups during non-influenza control periods.
  
  
  CONCLUSIONS
  Working-age adults with diabetes experience similar benefits from vaccination as elderly adults, supporting current diabetes-specific recommendations. However, these benefits were also manifest outside of influenza season, suggesting residual bias. Vaccination recommendations in all high-risk adults would benefit from randomised trial evidence.
authors.affiliation: Department of Public Health Sciences, University of Alberta, Edmonton, Canada.
authors.forename: Darren
authors.initials: D
authors.lastname: Lau
authors.forename: Dean T
authors.initials: DT
authors.lastname: Eurich
authors.forename: Sumit R
authors.initials: SR
authors.lastname: Majumdar
authors.forename: Alan
authors.initials: A
authors.lastname: Katz
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003920:Diabetes Mellitus / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008350:Manitoba / Q000453:epidemiology; D008875:Middle Aged; D009017:Morbidity / Q000639:trends; D011159:Population Surveillance / Q000379:methods*; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D014611:Vaccination / Q000379:methods*; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Clinical Epidemiology; Viral infection
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