Multi-Pathogen Wastewater-Based Epidemiology Before, During, and After the Milano-Cortina 2026 Winter Olympic and Paralympic Games: Monitoring of the Alpine Tourist Sewersheds of the Province of Trento

Given worldwide advances in wastewater-based epidemiology (WBE), its implementation is also emerging in international sporting events. The WBE application to a major international sporting event held under winter and cold-climate conditions remains unexplored. The Milano-Cortina 2026 Winter Olympic and Paralympic Games, hosted in the Alpine region, provided a unique opportunity to explore the potential of wastewater surveillance during the winter period, when seasonal diseases also drive pathogen circulation. This paper presents the results of the WBE surveillance conducted in the Province of Trento, over six months (November 2025-April 2026) and covering the periods before, during, and after the Winter Olympic and Paralympic Games. A total of 96 wastewater samples were collected from six wastewater treatment plants (WWTPs) serving the Fiemme and Fassa valleys, with a total census population of about 29,000 but reaching 143,000 population equivalents during tourist periods. The WBE monitoring involved quantitative analyses of SARS-CoV-2, influenza A/B, RSV A/B, and Norovirus GI/GII, as well as screening for measles. Norovirus GI/GII and RSV A/B circulated as the number of event-related visitors increased, whereas SARS-CoV-2 and influenza viruses remained at background or seasonal levels. Clinical surveillance data in the Province of Trento effectively complemented this multi-pathogen WBE. In conclusion, this experience provided non-invasive, community-wide information and demonstrated the operational feasibility and usefulness of WBE as a multi-pathogen sentinel tool for situational awareness to complement public health surveillance.