Researchers from Eawag, taking samples at Zurich’s Werdhölzli wastewater treatment plant on their hunt for traces of medicines. | Photo: Esther Michel, Eawag

The Swiss Federal Institute of Aquatic Science and Technology (Eawag) regularly tests the wastewater of roughly a quarter of the Swiss population for specific viruses – and also for traces of drugs. An analysis of both sets of data has revealed a link between the occurrences of respiratory viruses and of the medicines we use to treat their symptoms, such as having a fever.

However, a temporary increase in the consumption of drugs between 2021 and 2024 – such as antibiotics or cough medicine – also points to the existence of infectious diseases that are not being monitored in our wastewater. “Clinical data suggest rhinoviruses or an outbreak of whooping cough”, says Stephan Baumgartner, the lead author of the analysis. Wastewater analyses can provide insights into our true daily consumption of drugs in a manner that would be impossible through monitoring just the sales of medicines.

S. Baumgartner et al.: Insights into respiratory illness at the population level through parallel analysis of pharmaceutical and viral markers in wastewater. Nature Water (2025)