title: The association of seasonal influenza vaccination with pandemic influenza H1N1 2009 infection.
abstract: In 2010 Skowronski and colleagues reported that seasonal influenza vaccine appeared to increase the risk of pandemic influenza H1N1 2009 (pH1N1) infection during the first pandemic wave in Canada [1]. They suggested a number of possible explanations for their unexpected finding: firstly, that the results were an artefact of selection bias or confounding; secondly, that the results were due to partial mediation through a biological mechanism; and thirdly, that the results were due to a direct immune mechanism, such as antibody dependent enhancement [1]. In a recent paper in Vaccine, Rosella and colleagues have investigated in detail the first of these possibilities, confirming that it is unlikely an unidentified confounder could have explained the findings [2].
authors: Heath
authors: H
authors: Kelly
authors: Geoff
authors: G
authors: Mercer
authors: Benjamin J
authors: BJ
authors: Cowling
mesh_terms: D015986:Confounding Factors, Epidemiologic; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male
chemical_list: D007252:Influenza Vaccines