title: Effectiveness of A(H1N1)pdm09 influenza vaccine in adults recommended for annual influenza vaccination.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Pharmacy, Unit of PharmacoEpidemiology & PharmacoEconomics (PE2), University of Groningen, Groningen, The Netherlands. g.gefenaite@umcg.nl
authors.forename: Giedre
authors.initials: G
authors.lastname: Gefenaite
authors.forename: Margot
authors.initials: M
authors.lastname: Tacken
authors.forename: Jens
authors.initials: J
authors.lastname: Bos
authors.forename: Irina
authors.initials: I
authors.lastname: Stirbu-Wagner
authors.forename: Joke C
authors.initials: JC
authors.lastname: Korevaar
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Stolk
authors.forename: Bert
authors.initials: B
authors.lastname: Wolters
authors.forename: Marc
authors.initials: M
authors.lastname: Bijl
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Postma
authors.forename: Jan
authors.initials: J
authors.lastname: Wilschut
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Nichol
authors.forename: Eelko
authors.initials: E
authors.lastname: Hak
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011136:Polysorbates / Q000008:administration & dosage; D012189:Retrospective Studies; D013185:Squalene / Q000008:administration & dosage; D014611:Vaccination; D055815:Young Adult
chemical_list: D000276:Adjuvants, Immunologic; D007252:Influenza Vaccines; C089950:MF59 oil emulsion; D011136:Polysorbates; D013185:Squalene