Chicago plans to begin testing the city's sewage to gauge the level of SARS-CoV-2 infections there, the Chicago Tribune reports. As the virus appears to crop up in sewage samples about a week before people begin seeking treatment at hospitals, the hope is that testing will enable hospitals and healthcare workers to prepare and brace for an upswing in COVID-19 cases.
Other cities and even a university have adopted this testing approach. In April, Mariana Matus, the co-founder of Biobot Analytics, and her colleagues applied their company's testing approach to wastewater samples from Massachusetts to find they could detect SARS-CoV-2 in samples from after the pandemic began, but not before. The Verge reported in June that cities like New Haven, Connecticut, and Carmel, Indiana, adopted testing either by Biobot or similar testing by Yale scientists. Additionally, the University of Arizona tested wastewater from dorms to spot COVID-19 outbreaks.
The Tribune notes that, in Chicago, part of the challenge of implementing testing will be determining where in the 4,500 miles of city sewers to sample and navigating rivalries between the Chicago Department of Water Management and the Metropolitan Water Reclamation District. It adds that, currently, officials from the water district are sending samples from three treatment plants for analysis by Stanford University and University of Michigan researchers, who are sharing the results with researchers from Illinois universities who, in turn, are modeling whether neighborhood-level sampling could identify local hotspots.