USask researchers predicting COVID-19 case numbers using wastewater

With every flush, people in Saskatoon are helping a team of researchers predict COVID-19 cases in the city.

In collaboration with the City of Saskatoon and Saskatchewan Health Authority (SHA), University of Saskatchewan (USask) environmental scientists have been taking samples of wastewater to test levels of the novel coronavirus.

“An infected person would shed the virus through their feces and then it goes down with the wastewater down the drain. It takes a day or two to reach the water treatment plant,” USask enviornment and sustainability assistant professor Markus Brinkmann explained.

The team previously worked on other projects with the city, but pivoted when COVID-19 started to impact people in Saskatoon. The research now is a bit different because they were testing environmental DNA prior to the pandemic, but now have to test for RNA.

“This novel coronavirus is a single stranded RNA virus so we measure the RNA that’s in the wastewater,” USask environmental science professor John Giesy said about the testing.

This type of testing has been done with other viruses, like influenza. However, it’s the first time this team has tested for a virus in Saskatoon’s wastewater.

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The team started collecting samples in July when active cases in Saskatoon were relatively low. Cases began to rise in the fall. It’s the same trend seen with new active cases, but the wastewater samples showed the increase quicker as it accounts for people who are asymptomatic or haven’t been tested yet.

“What we can do is give a prediction of what things will look like in a week so our data is about seven to fourteen days quicker,” Giesy said.

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Although it doesn’t replace the need for SHA to test people, it can help predict what we can expect in the coming weeks.

“It’s helpful for public health officials to make decisions around what kind of measures they want to implement. Also for people in Saskatoon who might think about how careful they want to be while they are out,” Brinkmann said.

Brinkmann also notes the wastewater samples could give health officials an idea of when restrictions can be lifted as case numbers go down.

From samples collected this week, the team expects COVID-19 cases to continue to rise next week.

With more funding, they hope to continue their research and would like to eventually expand to other Saskatchewan cities.