Wastewater samples in Sask. show COVID-19 spike in Regina, peak in Saskatoon

The latest study of wastewater from University of Regina and University of Saskatchewan shows an increase of COVID-19 in both cities, with an exponential spike in Regina, while the viral load fell in some northern Saskatchewan cities.

Saskatoon entering 'uncharted' territory of COVID-19, researcher says

A peek at the UV filtering system used at the City of Saskatoon's wastewater treatment plant. Researchers from the University of Saskatchewan recorded a 25 per cent increase in the viral load of COVID-19. (Submitted by the City of Saskatoon)

A scan of sewage sample in four Saskatchewan cities shows an exponential increase in COVID-19 in Regina and a decrease in some of the province's northern cities, according to wastewater analyses from the University of Regina and University of Saskatchewan.

The latest report from the University of Regina says current viral levels of SARS-CoV-2 are more than 250 per cent higher than peak levels during the Alpha wave in April 2021. That means there is 2.5 times more COVID-19 present in Regina, according to the study.

"Initial analyses indicate that the levels will not decrease within the next reporting period," a post on the University's Facebook page read.

"Compared to the previous week, the viral levels have increased significantly and remain high."

Wastewater data can help predict COVID-19 caseloads in Saskatchewan cities. Saskatchewan shifted from reporting daily COVID-19 data in early February to weekly reporting.

COVID-19 case numbers are skewed, even with weekly reporting, because of testing restrictions, making it difficult for experts and the public to track COVID-19 in the province.

In Saskatoon, analysis released by scientists from the university's Global Institute for Water Security on Monday found there was a 25.5 per cent increase in the COVID-19 viral load of Saskatoon sewage samples while that load dropped in Prince Albert and North Battleford.

It's a relatively small shift in Saskatoon's viral load of COVID-19, given the city's 742 per cent increase reported a week ago, however, toxicology professor John Giesy wrote in an email that Saskatoon is in "uncharted " territory.

He said the data runs almost exactly two weeks ahead of hospitalizations, meaning that the high rate of COVID-19 found in the University's wastewater analysis foreshadows a looming spike in hospitalizations.

"The current wave driven by Omicron BA-2 is still going up and we are now at the greatest value we have ever seen," he said.

"If there is any good news, the rate of increase seems to be slowing." 

A seven-day moving average of viral load of SARS-CoV-2 in Saskatoon wastewater, as analyzed by the University of Saskatchewan. (Submitted by John Giesy/University of Saskatchewan)

Both Prince Albert and North Battleford had a reduced COVID-19 viral load, with researchers calculating a 16.5 per cent decrease and 20.1 per cent decrease respectively.

Treatment plant operators in Prince Albert said that the average daily flows in the past week were about 16 per cent more than the last report because of meltwater — and the decrease needs to be read with that in mind.

Saskatoon, Prince Albert and North Battleford cities based their change percentage on the average of three individual daily measurements compared to the weekly average of the previous week. Reporting for this data in Saskatoon ended on April 13, Prince Albert on April 11 and North Battleford on April 9. 

In all four cities, the highly contagious Omicron BA.2 subvariant made up more than 98 per cent of the COVID-19 viral load found in sewage samples.

In the previous week's report, the subvariant made up less than 90 per cent of all samples found in Saskatoon, Prince Albert and North Battleford. Analysis in Prince Albert only found the BA.2 subvariant was in 61 per cent of the samples.