Community and Hospital-Based Laboratory Surveillance for Influenza, Respiratory Syncytial Virus, and SARS-CoV-2 During the 2023-2024 Season, Lyon, France.

Influenza, respiratory syncytial virus (RSV) and SARS-CoV-2 are among the main respiratory viruses circulating in the population, with a significant burden on public health. While individuals at higher risk are more likely to develop severe symptoms leading to hospitalization, viral circulation in the community remains less extensively monitored. This study compared viral circulation between RELAB, a recently established community-based laboratory surveillance network (n = 22 843 tested patients) and hospital surveillance at the Hospices Civils de Lyon, France (n = 23 046 tested patients), for the season 2023-2024. For influenza and SARS-CoV-2, similar trends were observed in at-risk populations (children under 5 years and adults over 65 years) in both settings. Circulation of these two viruses was first detected in the community and insights from the young adult population (19-64 years) were only captured in the community network. Circulation of RSV was more intense in terms of number of cases and started in the pediatric population, and consequently was more represented in the hospital setting. In conclusion, this study highlighted the complementarity between community and hospital surveillance, as different populations and periods of viral circulation were observed.