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been collecting samples of untreated sewage weekly from nine large regional wastewater facilities. The lab runs a polymerase chain reaction (PCR) assay on the samples to amplify small seg- ments of DNA or RNA. In this case, the lab looks for the RNA present in COVID-19.
“It’s very similar to the assays that they would be running if you had a nasal swab...but obviously we’ve had to adapt them for monitoring for those same genetic targets in sewage,” Curtis said. “We can quantify the RNA target, which tells us specifically that this virus is there. We get that in terms of copies of that target per volume of sewage.”
Copies of that target go up or down to indicate increases or decreases in infection in the community that the wastewater plant serves.
He added that “the assays are really specific, and so you won’t be shedding anything like these targets into sew- age if you’re not infected. If we see the presence of it, particularly early on in something like this pandemic, we know there are infections in this communi- ty.” Furthermore, “whether you have a symptomatic or an asymptomatic infec-
tion, you’ll shed the virus.”
Curtis wrote code to generate dash-
boards that help other officials see and understand the results. One dashboard shows how the data has changed over time, while another plots concentra- tions of the virus, normalized by popu- lation, on a map of HRSD’s wastewater catchments.
A proof of concept for
future applications
Comparing those dashboards to VDH data showing infection rates in Chesa- peake, Va., got the attention of Cynthia Jackson, environmental health manager at the Chesapeake Health Department. “It was interesting to me how they mir- rored each other,” she said. “We can see detection [in the wastewater] a little bit earlier than our spikes. That’s what
stimulated our local interest.”
She decided to conduct testing at some of the 280 sewer pump stations in Chesapeake and worked with David Jurgens, the city’s director of public utilities, to determine the best places for testing. They based their decisions on the insights they wanted to learn, which included whether they could see
vaccination rates by census tract and whether the city’s numbers on the Vir- ginia Health Opportunity Index could help them identify where health care was less accessible or affordable.
“What it has allowed us to do is to develop some actionable strategies to help prevent and control [COVID-19] within our community levels,” Jack- son said. For instance, officials have targeted vaccination and testing out- reach in neighborhoods where they see infection rates increasing. In addition, the department has partnered with pro- fessors at Old Dominion University to create models that predict where infec- tions are most likely to increase.
Those efforts are proving valuable now, but Jurgens said the work is also a proof of concept for other applica- tions. “Because the markers show up in wastewater before somebody has symptoms, this is not simply a COVID thing, but this is a potential future science and life thing,” he said. “It’s been a really cool opportunity to get some incredibly meaningful and actionable data from a source [where] most people would never even think to look.” n
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