In Belgium, the wastewater surveillance program allows to monitor the circulation of three major respiratory viruses of public health concern. The surveillance program began in September 2020 with SARS-CoV-2, the virus causing COVID-19. In January 2024, influenza (the virus causing flu) and respiratory syncytial virus (RSV) were added. The surveillance covers 39% of the Belgian population and relies on the weekly analysis of wastewater samples. These samples are collected every Monday over a 24-hour period from influents of 30 wastewater treatment plants across Belgium, mainly in densely populated areas. The samples are tested for the presence of SARS-CoV-2, influenza and RSV.

The evolution of SARS-CoV-2, influenza and RSV over time is assessed using four activity levels: low, moderate, high and very high. These levels are defined at different geographical scales: national, regional, provincial, and individual treatment plant level. A weekly assessment of the SARS-CoV-2, influenza and RSV status in wastewater is published in the weekly report. Detailed information on the methodology can be found in the methodology appendix. Data are accessible through the federal geoportal, and general information about the program is available on the Sciensano website. The dashboard is updated every Monday.