Number of Austrian SARS-CoV-2 infections in the 2024/2025 season: Analysis of national wastewater data

ObjectivesAdaptation of SARS-CoV-2 policies requires information on contemporary infection trends. As SARS-CoV-2 infections are no longer actively tracked, indirect measures such as estimations based on wastewater data are needed.Study designThis is a retrospective observational study.MethodsWe estimated total SARS-CoV-2 infections in the entire population of Austria from April 1, 2024, to March 31, 2025, based on wastewater monitoring data. The applied method builds on a previously published approach that estimated infection prevalence during the pandemic by fitting wastewater measurements to seroprevalence data.ResultsBetween April 1, 2024, and March 31, 2025, we estimate 2.5 million new infections in Austria. Active infections peaked at 337,000 in late September and decreased thereafter. Infection rates in winter were substantially lower compared to previous years.ConclusionThe findings indicate the earliest annual fall/winter peak and the lowest annual infections since 2020. Policy makers, physicians and high-risk individuals should be aware of the ongoing seasonal SARS-CoV-2 infection waves and their variability in timing.