Brochure presenting the SEQ4EPI project and its results after three years of operation. Co-funded by the European Union, this project is led by Santé publique France and the National Reference Center for Respiratory Viruses (CNR-VIR). It aims to strengthen infectious disease surveillance in France through pathogen sequencing and to respond proactively to potential future health crises. Launched in October 2022 for a three-year term, SEQ4EPI relies on a network of laboratories and institutions. The project builds on the EMERGEN consortium, created in 2021 to address the COVID-19 crisis, and extends to other emerging pathogens, such as the Monkeypox virus and Influenza viruses. Between January 2022 and July 2024, SEQ4EPI strengthened genomic surveillance of SARS-CoV-2, conducting 135 prevalence surveys to track the spread of variants. The data collected were used in several scientific publications and epidemiological bulletins by Santé publique France. SEQ4EPI also supports the development of bioinformatics tools, such as ClusterFinder and SARSProbeMonitor, for identifying clusters and assessing mutations that affect SARS-CoV-2 detection. The project also includes an inventory of the sequencing capabilities and needs of French regional public health agencies. For more information, the brochure refers readers to the French and English web pages of Santé publique France and provides links to associated European partners and projects.