University of Groningen Effectiveness of A(H1N1)pdm09 influenza vaccine in adults recommended for annual influenza vaccination Gefenaite,

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. Citation: Gefenaite G, Tacken M, Bos J, Stirbu-Wagner I, Korevaar JC, et al. (2013) Effectiveness of A(H1N1)pdm09 Influenza Vaccine in Adults Recommended for Annual Influenza Vaccination. PLoS ONE 8(6): e66125. doi:10.1371/journal.pone.0066125 Editor: Benjamin J. Cowling, University of Hong Kong, Hong Kong Received February 21, 2013; Accepted May 1, 2013; Published June 20, 2013 Copyright: 2013 Gefenaite et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The work was supported by the University of Groningen, University Medical Center Groningen, the Netherlands. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: Kristin Nichol has served as a consultant to or on medical advisory boards for vaccine manufacturers in the past (or may in the future). Marc Bijl received research grants from Novartis and Sanofi, inclusive those interested in the subject of the manuscript; however, no financial support for contribution to this study was received. Joke Korevaar received a research grant from AstraZeneca, which was not related to the subject of this manuscript. Maarten J. Postma received research grants, honoraria and travel stipends from GSK Zeist NL, Amgen, GSK Bio Brussels, Shire, Pfizer, SPMSD NL, SPMSD Brussels, MSD, Sanofi, Novartis, Novo Nordisk, Jansen, Roche, Preglem, Boehringer Ingelheim, Viiv, Astra Zeneca, inclusive those interested in the subject of the manuscript; however, no financial support for the contribution to this study was received. Jan Wilschut received research grants, honoraria and travel stipends from GlaxoSmithKline (Zeist, Netherlands), SPMSD (Lyon, France), Crucell (Leiden, Netherlands), Solvay Biologicals (Weesp, Netherlands), Roche (Woerden, Netherlands), Mymetics (Leiden, Netherlands), Mucosis (Groningen, Netherlands), GlaxoSmithKline (Rixensart, Belgium), inclusive those interested in the subject of the manuscript; however, no financial support for contribution to this study was received. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. Other authors have declared that no competing interests exist. * E-mail: g.gefenaite@umcg.nl