This document summarizes the test-negative design study conducted by the Istituto Superiore di Sanità (National Institute of Health, ISS) within the Italian Influenza surveillance network (InfluNet) during the 2018-2019 influenza season. The study aimed to estimate seasonal influenza vaccine effectiveness against laboratory-confirmed influenza in Italy. A total of 2,526 patients presenting with influenza-like illness to participating general practitioners were enrolled. Of those, 1,177 tested positive for influenza and 1,349 tested negative. Preliminary results found significant differences in age distribution between cases and controls, with a higher proportion of cases among children and the elderly. Further analyses will estimate vaccine effectiveness stratified by age, virus subtype, and