Transmission dynamics of Norovirus GII and Enterovirus in Switzerland during the COVID-19 pandemic (2021–2022) as evidenced in wastewater
Noroviruses and enteroviruses are major causes of endemic gastrointestinal disease associated with substantial disease burden. However, viral gastroenteritis is often diagnosed based on symptoms, with etiology infrequently tested or reported, so little information exists on community-level transmission dynamics. In this study, we demonstrate that norovirus (NoV) genogroup II and enterovirus (EV) viral loads in wastewater reveal transmission dynamics of these viruses. We report NoV and EV concentrations in wastewater from 363 samples between December 5 2020 and October 10 2022 (sampled every second day). Virus concentrations in wastewater were low during 2021, and increased in 2022. Wastewater recapitulated periods of increased clinical cases, and also identified silent waves of transmission. We used the measured wastewater loads to estimate the effective reproductive number (R<sub>e</sub>). The R<sub>e</sub> for both NoV and EV peaked between 1.1 and 1.2. However, the usual seasonality of NoV transmission was upended by non-pharmaceutical interventions implemented to mitigate the COVID-19 pandemic, leading to correlated transmission dynamics of NoV GII and EV during 2021-2022. This highlights the use of wastewater to understand transmission dynamics of endemic enteric viruses and estimate relevant epidemiological parameters, including R<sub>e</sub>.
Authors
- Charles Gan (ORCID: https://orcid.org/0000-0001-6554-0954)
- Timothy R. Julian (ORCID: https://orcid.org/0000-0003-1000-0306)
- Htet Kyi Wynn
- Jana S. Huisman (ORCID: https://orcid.org/0000-0002-1782-8109)
- Tamar Kohn (ORCID: https://orcid.org/0000-0003-0395-6561)
- Michael Huber (ORCID: https://orcid.org/0000-0002-0384-0000)
- Shotaro Torii (ORCID: https://orcid.org/0000-0001-6655-7440)
- Irene K Voellmy (ORCID: https://orcid.org/0000-0003-2490-5261)
Institutions
- Swiss Tropical and Public Health Institute (CH)
- University of Zurich (CH)
- Living Systems (United States) (US)
- École Polytechnique Fédérale de Lausanne (CH)
- Swiss Federal Institute of Aquatic Science and Technology (CH)
- Massachusetts Institute of Technology (US)
Publication Details
- Journal
- Epidemics
- Published
- 2025-08-08
- DOI
- https://doi.org/10.1016/j.epidem.2025.100851
- Citations
- 4
- Primary Topic
- Viral gastroenteritis research and epidemiology
- Type
- article
- Field-Weighted Citation Impact
- 5.58
Funders
- Human Frontier Science Program
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Bundesamt für Gesundheit