Influenza vaccination uptake among at-risk patients in Switzerland-The potential of national claims data for surveillance.

Background: Swiss national surveillance of influenza vaccination uptake rates (VURs) relies on self-reported vaccination status. The aim of this study was to determine VURs among at-risk patients, namely, patients ≥65 of age and adult patients with chronic diseases, using claims data, instead of self-reported measures, to investigate factors of vaccine uptake, and to assess different methodological approaches to conduct vaccination surveillance.

Methods: In this retrospective cross-sectional analysis, we determined VURs in three influenza seasons (2015/2016-2017/2018).