This report was commissioned by the DGS from Santé publique France. Its purpose is to describe and understand how the VigilanS system operates as it was implemented in five pilot regions between 2015 and 2018, in order to identify the barriers and enablers to its implementation and to propose recommendations for future rollouts of the system in other regions. The findings presented are based on an analysis of qualitative data (document reviews, interviews, site visits, and focus groups) collected between September 2016 and December 2018 in the five pilot regions.