Ottawa

More coronavirus in wastewater could signal rise in cases, scientist says

Scientists monitoring Ottawa's wastewater say detected levels of the coronavirus changed course in early June coinciding with the end of Ontario's stay-at-home order.

Levels of coronavirus in Ottawa’s wastewater increasing since June 5

Robert Delatolla, co-lead investigator on Ottawa's coronavirus wastewater monitoring program, poses in front of a pumping station used to collect wastewater samples in April. (Adrian Wyld/Canadian Press)

Scientists monitoring Ottawa's wastewater say detected levels of the coronavirus changed course in early June, which coincided with the end of Ontario's stay-at-home order and could signal a rise in cases.

Robert Delatolla, a co-lead investigator on Ottawa's coronavirus wastewater monitoring program, says the recent rise of coronavirus levels found in wastewater samples is similar to increases seen at Christmas and earlier this spring.

In both cases, the nation's capital saw a surge of cases. 

"The total concentration of that little genome — that RNA fragment that we tested in the wastewater — is going up," said Delatolla, who is also an associate professor at the University of Ottawa.

"It coincided, unfortunately, with the reopening."

According to the most recent data, the levels of the coronavirus in Ottawa's wastewater have trended upward since June 5 after a steady decline.  

WATCH | COVID-19 in wastewater on the rise:

COVID-19 in wastewater is on the rise, which could mean another wave of infections is on the way

CBC News Ottawa

1 month ago
0:37
Robert Delatolla, a co-lead investigator on Ottawa's coronavirus wastewater monitoring program, says the recent rise in COVID-19 levels found in the city’s wastewater is similar to what scientists saw before previous surges in case numbers. 0:37

While the city's daily case totals have dropped significantly — with Ottawa Public Health reporting only 10 cases on Tuesday — the city's wastewater has often acted as an early warning system about the spread of COVID-19. 

Delatolla said increases in wastewater levels can often lead reported case totals by a week or more.  

"This feels very similar. We saw this in the last two waves," he said. 

It's unclear what's causing the increase — whether it signals more people are contracting the illness or that a smaller group is battling more severe cases. 

Another complicating factor is the comparatively high levels of vaccinations in Ottawa and how inoculations may affect the data researchers are examining, he said.

"What exactly does that mean? There's still a lot of science to be done here."

Watching for delta variant

Ontario's COVID-19 Science Advisory Table estimates the delta variant, first identified in India and thought to be more transmissible than previous variants and more resilient against currently available vaccines, accounts for about 40 per cent of all new cases in the province. 

In early April 2021, researchers who measure levels of COVID-19 in Ottawa's wastewater found the highest levels since early June 2020. Those levels steadily declined for weeks and have ticked back up in recent days. (. (613covid.ca))

In a recent interview with CBC News, Dr. Doug Manuel, a senior scientist with The Ottawa Hospital who does the modelling of local numbers, said it's only a matter of time until the delta variant becomes the dominant strain in Ottawa. 

"It's in our wastewater," he said.

Delatolla said the delta variant could be playing a hand in the recent increase. 

"We're hoping that's not the reason here. But we're definitely going to continue to watch the clinical metrics, continue to watch the new daily cases and to continue to watch hospitalizations."

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