Latest wastewater analysis predicts COVID-19 cases could trend down in Saskatoon

Scientists analyzing Saskatoon's wastewater for the virus that causes COVID-19 saw a spike one week followed by a large drop the next.

The most recent study, for the period of April 21 to 27, showed a 70 per cent drop in the COVID-19 viral load.

The percentage of cases identified as the B117 variant of concern dropped to 70 per cent from 80 per cent in the latest study. The latest results also showed traces of the P1 variant first identified in Brazil.

Analysis from mid-April showed the level of COVID-19 in the wastewater had jumped more than 300 per cent.

Saskatoon hasn't seen the surge in cases that data suggested might come, though it may be on its way, as new cases in jumped to 81 on Tuesday from 29 cases on Monday.

Dr. John Giesy, a professor at the University of Saskatchewan and the Global Institute for Water Security, said there could be several reasons why Sskatoon has yet to see more reported cases, including the shift toward more cases being the B117 variant first identified in the United Kingdom.

"We're learning new things every day and there are a lot of open questions, particularly with some of these new variants on how they behave," Giesy said.

"We know that [B117] causes more illness, more severe illness for longer. What we don't know is what it does to the shedding of virus while people are spreading more virus or for longer."

He also said some people who have COVID-19 may not have shown up in the province's testing during the past two weeks.

"There were probably people getting [infected] that weren't sick enough to report to hospital or end up in ICU," he said.

"They were still home, still shedding virus and probably [were] younger."

Giesy and his fellow researchers report all of their data to the city, public health and to the Public Health Agency of Canada, which also tests the data for accuracy.

Giesy said researchers at the University of Regina are doing similar studies and he'd like to share data to get a better picture of what's happening.

"We could see if they saw a similar phenomenon."

He said the studies aren't trying to predict actual case numbers, but rather whether cases are trending up or down.

"So my interpretation is over the next few weeks that we should see a decrease in case numbers."

Giesy said there several reasons case numbers may be coming down. These include more people getting vaccinated and the seasons changing.

"Summer's coming. These things generally wane in the summer. So that's good news," he said. 

"The wildcard is these variants that are coming in."

Giesy's biggest fear is some of these variants —  especially the P1 variant — might be able to circumvent the vaccines.