Since September 2020, researchers at the University of California, Davis have been monitoring wastewater on the UC Davis campus and in the city of Davis for COVID-19 as part of the Healthy Davis Together program. A new article published Feb. 8 in Proceedings of the National Academy of Sciences reviews their experiences as well as the benefits and limitations of wastewater testing as a public health tool in the COVID-19 pandemic.
Assistant Professor Heather Bischel and PhD student Hannah Safford, Department of Civil and Environmental Engineering, and Karen Shapiro, Associate Professor in the School of Veterinary Medicine, manage the city/campus wastewater monitoring program, which now includes weekly, tri-weekly, or daily collections from over 50 locations across the UC Davis campus and the City of Davis sewer systems. Their findings supported students returning to campus and helped officials understand the spread of COVID-19 in the community.
“Continued deployment of wastewater-based epidemiology in a way that takes into account the needs of policy makers and pragmatically weighs costs and benefits will undoubtedly go a long way towards ending the pandemic,” they said. writing.
Advantages and limitations
Because infected people start shedding the virus days before they develop symptoms, sewage monitoring can provide an early warning of infection in the community. The approach is also more cost-effective than individual large-scale clinical trials when it comes to gathering data on disease levels in an area.
But as Safford, Shapiro, and Bischel explained, wastewater monitoring also has limitations. It is less effective as an early warning system when community transmission is high. And while relatively inexpensive, wastewater monitoring doesn’t come free. This requires specialized equipment such as autosamplers, as well as personnel to collect, process and analyze the samples. Investing in wastewater monitoring can also divert time and resources from other efforts.
Finally, deciding how to act on wastewater data can be difficult, because the results don’t show who may be infected: they can only indicate a neighborhood or building complex (like a college dorm) of potential concern. In Davis, Healthy Davis Together has used sewage data to strategically target emails, text alerts and incentives encouraging Davis residents to get tested when local virus levels rise.
The PNAS The article includes a series of recommendations for the use of wastewater monitoring in the response to COVID-19. These include avoiding redundancy with clinical trials, designing thoughtful sampling and data analysis plans, defining action thresholds, monitoring fewer sites but more frequently, build on existing infrastructure and be prepared to adapt and communicate with other practitioners, epidemiologists and public health officials.