Rising levels of COVID-19 detected in Toronto wastewater as province drops mask mandate

On New Year’s Eve, as Omicron overwhelmed the testing system, the province limited access to PCR testing to only high-risk settings and people.

Without these case numbers to draw on to get an accurate picture of community spread, sewage COVID DNA fingerprinting testing, which began in Canada in April 2020, has come to the fore.

Fortunately, the PCR eligibility changes “do not affect the number of people who go to the bathroom,” said Robert Delatolla, a professor at the University of Ottawa whose lab tracks COVID in Ottawa’s sewage. .


Wastewater monitoring works by monitoring the level of SARS-CoV-2, the virus that causes COVID, in water carrying feces after we flush. Samples are being taken from sites across the province, providing an early indicator of rising cases, as virus fragments will be detected in feces before anyone is sick enough to go to hospital .

“It can really tell us, are we out of the woods? How are we?” said Delatolla. “It gives you that information where you can make those choices for yourself, and that fills that void that we have now.”

Claire J. Oswald, an associate professor in the department of geography and environmental studies at Ryerson University who works on samples from the Humber sewage treatment plant in Toronto, said there may be ” highs and lows” now that overall COVID levels have dropped from Omicron’s peak.

Oswald credits the labs doing the sewage testing and the province for organizing them, calling them a “success story” that “hopefully can be leveraged for other things beyond COVID,” like tracking flu case.

“For people wondering, ‘Does this really work?’, it does,” said Dr. Eric Arts, Canada Research Chair in Viral Control and professor of immunology. at Western University. “The virus remains relatively stable in wastewater, so we can monitor it. This matched the cases almost perfectly when we were monitoring the cases.

Arts, along with other researchers from other universities, monitors wastewater for the province and the Public Health Agency of Canada. He noted that this type of surveillance likely provides a better representation of the total number of cases in Ontario simply because many infected people are not getting tested.

“Now we can identify regions that might have an increase in transmission,” he said. “If we needed to, we could be very specific in putting in place more stringent public health measures in a specific region.”

Jüni says he’s worried that if Ontarians start embracing the newly allowed freedoms, at the same time as we drop the masking warrants, cases could start to rise again.

“It could be too much in terms of high-risk contact and transmission,” he said. “We first want to make sure that sewage levels remain relatively stable or, if they rise, stabilize again. The longer we wait, the closer we get to spring and the more the good weather will help us. »

Kenyon Wallace is a Toronto-based investigative reporter for the Star. Follow him on Twitter: @KenyonWallace or contact him by email: [email protected]

May Warren is a Toronto-based breaking news reporter for the Star. Follow her on Twitter: @maywarren11