Influenza vaccination strategies aim at protecting high-risk population from severe outcomes. Estimating the effectiveness of seasonal vaccines against influenza related hospitalisation is important to guide these strategies. The objective is to measure the population effectiveness of influenza vaccine in patients hospitalized with virologically confirmed influenza laboratory during 3 influenza seasons 2013/2014, 2014/2015 and 2015/2016 in a French hospital network. An interim analysis is provided for each influenza season and an overall analysis of 3 seasons.