Four recently described observational studies from Canada found that receipt of 2008–09 trivalent influenza vaccine (TIV)

http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19616


Four recently described observational studies from Canada found that receipt of 2008–09 trivalent influenza vaccine (TIV) was associated with increased risk of pandemic influenza A(H1N1)2009 during the spring and summer of 2009 [1,2]. Determining whether a seasonal influenza vaccine that does not contain pandemic viral antigens can affect one’s risk of subsequent infection with the pandemic strain has important implications for public health, as well as our understanding of the immunopathogenesis of influenza infection. Household transmission studies are well-suited to examine this issue because prospective, active follow-up of household contacts can avoid many types of selection biases known to be associated with case-control studies [1].


http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19616