Saskatoon sewage tests point to upcoming increase in COVID-19 cases

A new tool developed by researchers at the University of Saskatchewan is predicting an increase in COVID-19 cases in Saskatoon by looking at the city's sewage. 

In partnership with the City of Saskatoon and the Saskatchewan Health Authority, researchers have been testing samples of the city's wastewater for the virus since July. 

Because infected people shed traces of the virus through their feces, tracking the amount of the virus circulating in the city's wastewater can help determine how many people in the city are sick. 

This should predict trends in case numbers ahead of the testing data, reflecting people who have the virus but are not showing symptoms. 

"We think we can give health officials at least a week's notice on changes in the trend line," said ecotoxicologist John Giesy. "Based on the latest data which shows the trend line is going up, I am predicting we will see a rise in cases for the next couple of weeks."

The researchers' most recent findings suggest case numbers in the city will continue to rise.  

"Over the past two weeks, we have seen an exponential increase in virus copies in the wastewater," said toxicologist Markus Brinkmann. 

Kerry McPhedran is an associate professor of engineering at the University of Saskatchewan and part of the research group at the university.

He said the project isn't quite at the stage where they can pinpoint where in the city the positive cases are coming from.

"Right now we're just doing the one test so it's all the wastewater coming from all the city going into the Saskatoon wastewater treatment plant," McPherdan said. "There has been talk about doing certain locations in the city; we have some issues in ethics involved with that if we're kind of trying to pinpoint."

Going forward, the research team is hoping to secure more funding to test Saskatoon's wastewater more often and to expand to more communities. 

"In particular, Prince Albert and Regina would be good locations to do it in," McPhedran said. "If we could do about three samples a week, we could process those in our lab within two to three days."

The Saskatchewan Health Authority said this kind of advance warning tool can help public health officials decide where they need to be focusing their efforts. 

"The early findings are shaping the public health response in Saskatoon," said SHA medical health officer Dr. Simon Kapaj. "We believe this tool could assist other major cities in Saskatchewan."