In a new study, researchers took daily samples from the New Haven-area wastewater treatment plant.
They were able to track the progression of COVID-19 up to seven days before the same pattern is reported by compiled testing data from the New Haven metropolitan area.
Since March 19, the research team has been collecting samples from the wastewater treatment plant serving New Haven, East Haven, Hamden, and parts of Woodbridge, CT.
The curve of the progression as seen in the samples is similar in shape to the number of confirmed cases reported by testing, but the SARS-CoV-2 concentrations lead the testing by approximately one week.
The research was conducted by a team at Yale University.
The progression of COVID-19 in a community is typically tracked by testing symptomatic cases and evaluating the number of positive tests.
However, it can take up to five days for symptoms to emerge in someone who’s infected and contagious, so earlier detection of the virus in a community could be crucial to slow its spread.
The study’s results are from the 10-week period from March 19 to June 1.
The researchers, though, will continue taking samples through the fall, so if there’s an uptick in cases, they expect the sewage samples to show that—possibly well before these new cases are diagnosed.
Specifically, they are collecting samples of primary sludge, created when solids in municipal raw wastewater first settle in treatment facilities.
The team says sludge is particularly useful for their purposes because it provides a highly concentrated and well-mixed sample and has been shown to contain a wide range of human viruses.
The method has important implications for low-income countries with big gaps in testing and can help inform decisions about whether to reopen parts of a particular city or region.
It’s an inexpensive method and very similar to the one used in many low-income countries to test for polio in communities—that would make adopting the research team’s method relatively easy.
The World Bank has expressed interest in piloting the program in a few cities very soon in South Asia to see how well it scales up to larger populations.
One author of the study is Jordan Peccia, the Thomas E. Golden, Jr. Professor of Chemical & Environmental Engineering.
The study is published in Nature Biotechnology.
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