Santé publique France was asked by the General Directorate of Health (DGS) to provide guidance on setting the start and end dates for the next prevention campaign against RSV bronchiolitis in newborns for the 2026–2027 season, in mainland France as well as in each of the overseas departments and regions (DROM) (request No. 26-A-00047 dated May 28, 2026, attached).