COVID-19 levels decline in Saskatoon and Prince Albert wastewater samples

Researchers at the University of Saskatchewan say levels of COVID-19 were down in Prince Albert and Saskatoon in the latest tests of wastewater samples.

Researchers with the university's Global Water Futures program have been analyzing wastewater samples from Saskatoon, North Battleford and Prince Albert for COVID-19 since summer 2020.

The study's results can help predict a rise or fall of COVID-19 diagnoses about a week in advance.

The latest samples show the week-over-week SARS-CoV-2 viral RNA load in Saskatoon's wastewater decreased by 36.2 per cent. 

The viral load is still the ninth highest observed during the pandemic and is greater than the 10-week average. 

The viral load in Prince Albert's wastewater was down 14.5 per cent from the previous week, but still the fifth highest viral load recorded.

North Battleford's viral load remained virtually unchanged, down just 0.5 per cent.

The team's lead researcher, John Giesy, said the results "indicate that we are likely near the peak of this wave, but the model projects that infection will continue at or near the present level for another few weeks before declining."

The Omicron sub-variants account for all of the viral load in the three cities.

Giesy said the Battlefords and Prince Albert seem to always lag behind Saskatoon.

"They didn't go up anymore and Saskatoon went down about 40 per cent," he said.

"So have we hit the peak in Saskatoon? Maybe, but, you know, it's surprised us before when we got a double dip. It went down a little bit and then the next week it was back up again."

Giesy and his wife are recovering from COVID-19.

He said they came down with COVID after a trip to Alberta and southern Saskatchewan.

Giesy said it started with a cough on a Friday, and then he was hit hard by the virus over the next couple of days.

"I just couldn't stay awake. I was just so fatigued and just felt … achy, feverish, out of sorts," he said.

Giesy said it took almost two weeks to fully recover.

"Fortunately for us, it it didn't leave us with any long term issues that we know of yet," he said. 

He said modelling suggests the viral load should still be increasing.

"What [the modelling] looks at is how many people have been infected and what the pool of people to yet be infected is," he said. "So over time, as more and more people, like the wife and I catch it, we're less likely, at least, historically to get it again.

"But now with the new sub-variants, even those bets are off. People are getting sick, you know, two weeks after they got it, they get sick again. So who knows? We'll see what happens next week, but you know, it looks like we've probably hit the peak."

Giesy said it is becoming harder to assign a viral particle to a particular strain or sub-variant.

"It turns out that there is recombination of the mutations we monitor for the various strains, so they are all getting 'combined' together and the 'marker mutations' are no longer unique to a particular strain," he said.

"We will continue to do the best we can and develop new targeted assays as defined strains emerge."

Meanwhile, results from the University of Regina wastewater study show COVID-19 levels are the highest in that city since the height of the last Omicron wave in April.

The study shows the SARS-CoV-2 viral load is now 72 per cent of April's highest levels.

The numbers are considered to be moderately high on a scale that has four levels: low, moderate, moderate-high, high.