Wastewater testing shows COVID-19 may be 'starting to plateau' in Kitchener and Cambridge

Wastewater testing in the Region of Waterloo shows the Omicron variant of COVID-19 has pushed infection levels to more than 10 times higher than ever before but there are early indications that infections may be starting to level off.

Thursday's data published by the Region of Waterloo contains the first sign of hope for a slowing down of infection during the latest wave of the pandemic.

The team monitors for signs of COVID-19 in sewage, expressed as copies per one millilitre (mL) of effluent. 

"In Waterloo the wastewater signal continues to increase but there may be indications of the signal starting to plateau in Kitchener and Cambridge," said the update, posted to the Region of Waterloo's COVID-19 wastewater surveillance page.

That plateau started on Jan. 4, and continued for the next four to five days, said professor Mark Servos, the Canada Research Chair in Water Quality Protection, and the person leading the University of Waterloo's wastewater study. 

For example, the seven-day average of the wastewater signal in Kitchener on Dec. 28 was 139 copies/mL. By Jan. 1 that number increased to 209 copies/mL. A few days after that, it appears to have levelled off.

The seven day-average for the COVID-19 wastewater signal between Jan. 4 and Jan 8 was:

• Jan. 4: 248 copies/mL.
• Jan. 5: 273 copies/mL.
• Jan. 6: 264 copies/mL.
• Jan. 7: 265 copies/mL.
• Jan. 8: 273 copies/mL.

Servos told CBC Kitchener-Waterloo there's still a lot of variability in the data, but a similar plateau is being observed by other wastewater monitoring groups in Ontario. 

First sign of decline

The number of new cases and hospitalizations is also stabilizing, said Dr. Peter Juni, the scientific director of Ontario's COVID-19 Science Advisory Table.

"What we continue to see is test positivity going down. That makes me cautiously optimistic," Juni said.

"Again, what we are seeing is that there is a slowing down of this tremendous slope upwards of hospital occupancy. Let's pay careful attention to Tuesday and Wednesday — do we start to see things plateauing and that we are on the right way."

This is the first hint that infections may be slowing in the population. At the end of December, the Ontario government scaled back PCR testing to only high-risk people. It has meant the published numbers of daily case counts now vastly under-represent the actual number of infections both provincially, and in local health units. 

The University of Waterloo has been keeping track of the concentration of COVID-19 virus levels through the community's wastewater for about a year now.

"Everybody in the morning takes a poop. If the virus is in your body, it gets transferred into your digestive tract and comes out as feces and that flows down through our collection pipes, through the wastewater treatment plant and we're able to track the sample there in treatment plant that represents the whole community," said Servos in an interview with The Morning Edition's host Craig Norris on Thursday.

Tracking COVID-19 through wastewater as clinical testing systems overwhelmed

3 years ago

Duration 2:04

As testing systems become maxed out across the country, some experts are turning to wastewater testing as a way to determine how much COVID-19 is really in our communities.

Solid indicator

In March, the Government of Ontario spent $12 million to fund 13 wastewater treatment projects across Ontario. 

Over the past year that Servos and his team have been monitoring wastewater in the region, the wastewater trends have mirrored what was happening in public heath's reporting, said the region's medical officer of health, Dr. Hsiu-Li Wang on Jan. 7.

"It correlated really really well with our clinical cases."

And with testing restrictions what they are — she said the public health unit has "no way to say for sure" what the true infection rate is in Waterloo region right now. That makes wastewater testing the next best indicator. 

"Because wastewater has tracked extremely well over the last year and a half, we know it's a very effective tool; showing the increase in the clinical cases or the drop," said Servos. 

"It's such an independent way of monitoring community infection."

Going forward, Servos said he can see the system used to monitor other infectious diseases, not just COVID-19.