Effectiveness of A(H1N1)pdm09 influenza vaccine in adults recommended for annual influenza vaccination

Giedre Gefenaite*, Margot Tacken, Jens Bos, Irina Stirbu-Wagner, Joke C. Korevaar, Ronald P. Stolk, Bert Wolters, Marc Bijl, Maarten J. Postma, Jan Wilschut, Kristin L. Nichol, Eelko Hak

*Corresponding author for this work

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    INTRODUCTION: Because of variability in published A(H1N1)pdm09 influenza vaccine effectiveness estimates, we conducted a study in the adults belonging to the risk groups to assess the A(H1N1)pdm09 MF59-adjuvanted influenza vaccine effectiveness.

    METHODS: VE against influenza and/or pneumonia was assessed in the cohort study (n>25000), and vaccine effectiveness against laboratory-confirmed A(H1N1)pdm09 influenza was assessed in a matched case-control study (16 pairs). Odds ratios (OR) and their 95% confidence intervals (95% CI) were calculated by using multivariate logistic regression; vaccine effectiveness was estimated as (1-odds ratio)*100%.

    RESULTS: Vaccine effectiveness against laboratory-confirmed A(H1N1)pdm09 influenza and influenza and/or pneumonia was 98% (84-100%) and 33% (2-54%) respectively. The vaccine did not prevent influenza and/or pneumonia in 18-59 years old subjects, and was 49% (16-69%) effective in 60 years and older subjects.

    CONCLUSIONS: Even though we cannot entirely rule out that selection bias, residual confounding and/or cross-protection has played a role, the present results indicate that the MF59-adjuvanted A(H1N1)pdm09 influenza vaccine has been effective in preventing laboratory-confirmed A(H1N1)pdm09 influenza and influenza and/or pneumonia, the latter notably in 60 years and older subjects.

    Original languageEnglish
    Article numbere66125
    Number of pages6
    JournalPLoS ONE
    Issue number6
    Publication statusPublished - 20-Jun-2013


    • Adjuvants, Immunologic
    • Adolescent
    • Adult
    • Case-Control Studies
    • Female
    • Humans
    • Influenza A Virus, H1N1 Subtype
    • Influenza Vaccines
    • Influenza, Human
    • Male
    • Middle Aged
    • Netherlands
    • Polysorbates
    • Retrospective Studies
    • Squalene
    • Vaccination
    • Young Adult

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