Dec. 10, 2021 -- A number of U.S. cities have detected the Omicron variant by running tests on wastewater.

Scientists have been testing wastewater since the early days of the pandemic because they know infected people shed the coronavirus through their feces. Wastewater testing can provide an early warning system because it may detect a variant days before personalized testing does.

In Texas, the Houston Health Department regularly tests the city’s wastewater for the coronavirus and recently added Omicron to the list of variants to look for. Testing conducted Nov. 29-30 found Omicron traces at eight of Houston’s 39 wastewater treatment plants, reported Houston Public Media, a service of the University of Houston.

“We’ve seen a little bit of an uptick in the total amount of virus in the wastewater, so that would suggest to us that in about two weeks, we’re probably going to start seeing more hospitalizations for patients with COVID,” said David Persse, MD, Houston’s chief medical officer.

The Colorado Department of Public Health and Environment said Omicron was found in wastewater in Boulder, and testing recently confirmed the Omicron variant was in samples from wastewater plants in the California towns of Sacramento and Merced, NPR reported.

The California wastewater samples were tested by an outside lab that partners with Stanford University and the Sewer Coronavirus Alert Network (SCAN). Two scientists involved with SCAN explained how the testing works.

“Municipal sewage treatment plants take samples of the solids that settle in their tanks and send them to a lab for testing. The results come back within 24 hours. That quick turnaround means public health officials can see how prevalent the virus and its variants are in a community, which foreshadows a rise in cases,” Alexandria Boehm, PhD, a professor of civil and environmental engineering at Stanford University, and Ekemini A. U. Riley, PhD, founder and president of the Coalition for Aligning Science, wrote in The Hill.

The SCAN testing also has the benefit of ruling out the presence of Omicron in other cities.

Boehm and Riley said wastewater testing can detect a rise in COVID cases days before personalized testing and gives public officials a jump on how to respond and deploy resources. They called for wider use of wastewater testing across the nation.

Show Sources

NPR: “Poop sleuths hunt for early signs of omicron in sewage.”

Houston Public Media: “The COVID-19 omicron variant is likely already spreading in Houston. Here’s how we know.”

The Hill: “Wastewater provides a solution for monitoring omicron's spread.”

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