PLoS ONE (Jan 2011)

I-MOVE multi-centre case control study 2010-11: overall and stratified estimates of influenza vaccine effectiveness in Europe.

  • Esther Kissling,
  • Marta Valenciano,
  • Jean Marie Cohen,
  • Beatrix Oroszi,
  • Anne-Sophie Barret,
  • Caterina Rizzo,
  • Pawel Stefanoff,
  • Baltazar Nunes,
  • Daniela Pitigoi,
  • Amparo Larrauri,
  • Isabelle Daviaud,
  • Judit Krisztina Horvath,
  • Joan O'Donnell,
  • Thomas Seyler,
  • Iwona Anna Paradowska-Stankiewicz,
  • Pedro Pechirra,
  • Alina Elena Ivanciuc,
  • Silvia Jiménez-Jorge,
  • Camelia Savulescu,
  • Bruno Christian Ciancio,
  • Alain Moren

DOI
https://doi.org/10.1371/journal.pone.0027622
Journal volume & issue
Vol. 6, no. 11
p. e27622

Abstract

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BackgroundIn the third season of I-MOVE (Influenza Monitoring Vaccine Effectiveness in Europe), we undertook a multicentre case-control study based on sentinel practitioner surveillance networks in eight European Union (EU) member states to estimate 2010/11 influenza vaccine effectiveness (VE) against medically-attended influenza-like illness (ILI) laboratory-confirmed as influenza.MethodsUsing systematic sampling, practitioners swabbed ILI/ARI patients within seven days of symptom onset. We compared influenza-positive to influenza laboratory-negative patients among those meeting the EU ILI case definition. A valid vaccination corresponded to > 14 days between receiving a dose of vaccine and symptom onset. We used multiple imputation with chained equations to estimate missing values. Using logistic regression with study as fixed effect we calculated influenza VE adjusting for potential confounders. We estimated influenza VE overall, by influenza type, age group and among the target group for vaccination.ResultsWe included 2019 cases and 2391 controls in the analysis. Adjusted VE was 52% (95% CI 30-67) overall (N = 4410), 55% (95% CI 29-72) against A(H1N1) and 50% (95% CI 14-71) against influenza B. Adjusted VE against all influenza subtypes was 66% (95% CI 15-86), 41% (95% CI -3-66) and 60% (95% CI 17-81) among those aged 0-14, 15-59 and ≥60 respectively. Among target groups for vaccination (N = 1004), VE was 56% (95% CI 34-71) overall, 59% (95% CI 32-75) against A(H1N1) and 63% (95% CI 31-81) against influenza B.ConclusionsResults suggest moderate protection from 2010-11 trivalent influenza vaccines against medically-attended ILI laboratory-confirmed as influenza across Europe. Adjusted and stratified influenza VE estimates are possible with the large sample size of this multi-centre case-control. I-MOVE shows how a network can provide precise summary VE measures across Europe.