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Thorax doi:10.1136/thoraxjnl-2012-203109
  • Epidemiology
  • Original article

Effectiveness of influenza vaccination in working-age adults with diabetes: a population-based cohort study

Open Access
  1. Jeffrey A Johnson1
  1. 1Department of Public Health Sciences, University of Alberta, Edmonton, Canada
  2. 2Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
  3. 3Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada
  1. Correspondence to Dr Jeffrey A Johnson, 2-040G Li Ka Shing Center for Health Research Innovation, 8602 112 Street, Department of Public Health Sciences, University of Alberta, Edmonton, Canada, AB T6G 2E1; jeff.johnson{at}ualberta.ca
  • Received 7 December 2012
  • Revised 7 February 2013
  • Accepted 2 March 2013
  • Published Online First 27 March 2013

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.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/3.0/ and http://creativecommons.org/licenses/by-nc/3.0/legalcode

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