Testing wastewater helps epidemiologists see where COVID-19 is spreading and what variants are dominant.

COLORADO, USA — While we’re all used to getting clues about how and where COVID-19 is spreading through things like testing, the state has another useful tool – our toilets. 

The COVID situation here in Colorado is one of the worst in the country right now. We know cases, hospitalizations and the positivity rate are all going up. Now, epidemiologists are also finding more COVID in wastewater.

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“We’re seeing our wastewater surveillance mirror what we’re seeing in our human illness,” said Rachel Jervis, an Epidemiologist with the Colorado Department of Public Health and Environment (CDPHE). “When someone has COVID, we’ve found that just under 50% of people with COVID shed COVID in their stool regardless of whether or not they have symptoms.”

The state’s wastewater testing shows high rates of COVID nearly everywhere, from Fort Collins to Denver and down to Pueblo. Jervis said it’s been going up since the summer.

“By testing wastewater we can identify how much COVID there is in a community without having to rely on individuals seeking medical care and getting tested,” said Jervis. 

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CDPHE has been testing wastewater for COVID for much of the pandemic. They can tell which variant is spreading most in the state.

Right now, Jervis it’s nearly all Delta variant being flushed down the drain in waste. The state is ready to test wastewater moving forward to see if other variants pop up in Colorado.

“We’re looking at the wastewater to see what genetic markers indicate what variants,” Jervis said. “What we’re seeing in that wastewater is a lot of the Delta variant. Then the human case data is matching that. Viruses mutate and we expect to see different variants. While we are always tracking and looking in human specimens for that, wastewater gives us another opportunity to look for that.”

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Right now, CDPHE partners with 21 sewer sheds to test the wastewater up and down the front range. 

The health department said it is hoping to partner with more water utilities going forward to test more wastewater around the state.