Estimación de la efectividad de la vacuna antigripal en España mediante un diseño de estudio epidemiológico de casos y controles negativos

Resum

Conclusion in the post-pandemic phase 1. Effectiveness of the 2010-2011 seasonal trivalent influenza vaccine in Spain: preliminary results of a case¿control study The cycEVA study was able to provide an early intraseasonal estimate of the effectiveness of the seasonal vaccine nine weeks since the epidemic started. It suggested a protective effect of the vaccine against all types of influenza viruses. This effect was also seen in the group eligible for vaccination; however, the effect was lower than that reported in the previous season(129). It also demonstrated that intraseasonal vaccine effectiveness estimates were possible by conducting observational studies, with an acceptable additional effort, within the framework of a well-organized influenza surveillance system meeting the criteria of the European Influenza Surveillance Network. The cycEVA study was continuing in Spain and ILI cases were still being recruited while sporadic circulation of influenza viruses was registered in the participating regions. Therefore we expected that at the end of the season the sample size could allow more precise estimates of vaccine effectiveness and could enable to control for other confounding factors known to influence vaccine effectiveness. In addition, the I-MOVE multicentre study, pooling data from eight European countries including Spain, was also able to present even more precise estimates.