Ottawa scientists develop test to detect COVID-19 variant in wastewater
OTTAWA -- Ottawa scientists who have been studying the level of COVID-19 in the city's wastewater have developed a test to determine the level of at least one of the variant strains.
Speaking to CTV Morning Live on Friday, Dr. Tyson Graber, a research associate at the CHEO Research Institute in Ottawa, said his team has found a way to detect the B.1.1.7 variant in wastewater samples.
"We can announce that we have a test to detect the B.1.1.7, commonly known as the U.K. variant, in wastewater and we're quite satisfied that this works," he said.
Graber, the co-lead investigator on the COVID-19 wastewater project, said that as of Jan. 16 there was no detection of the variant in Ottawa's sewage, but that doesn’t mean it's not present in the community.
"It's here at significantly low levels," he said. "Low enough that we cannot detect it with this test."
At least three cases of the B.1.1.7 variant have been confirmed in Ottawa, according to health officials. Graber said he estimates there would need to be at least several dozen infections for the viral signal to be detected in the wastewater.
"It is surprisingly difficult to come up with this number. Testing in wastewater is still an inexact science," he said. "The ballpark figure I've been throwing around is 50 to 100 cases that we'd need in Ottawa before we can actually have detection."
Graber said the team at the CHEO Research Institute and the University of Ottawa are working on tests to detect the B.1.351 (first detected in South Africa) and P1 (first detected in Brazil) variants of COVID-19 as well.
While the number of confirmed variant cases in the city is currently low, Graber pointed out that was the case with COVID-19 in general last year.
"It's not a matter of if this comes here, it's when," he said. "We have a short-term memory. We don't remember what happened in February and March of last year. Only a few cases were hanging around. Not a big deal. We can see how quickly this changes."
Graber said the community must remain vigilant about the spread of COVID-19 and continue to wear masks, keep physical distance and limit contact with others.
The wastewater monitoring project reports data back to early June, 2020. Ottawa is the first community in Canada to conduct and report on the amount of COVID-19 in the local wastewater on a regular basis.
"People with COVID-19 shed the causative SARS-CoV-2 virus in their stool, regardless of whether they have symptoms, receive a COVID-19 test or ever are diagnosed," a statement on the wastewater tracking page says. "Thus, in contrast to assessing community COVID-19 levels by measuring the number of active cases, which may miss asymptomatic infections as well as be subject to limited test availability, wastewater surveillance consistently captures most of the population with COVID-19 given that everyone goes to the washroom."
Graber said, locally, Ottawa appears to be in a downward trend.
"We can see, in the last couple of days, a significant downward trend in the last few days of data. We're on the way down, it's just a question of how fast," he said. "It's still correlating very well with the case numbers and with the positivity rate in Ottawa."
On Friday, Ottawa's average testing positivity rate fell to 1.6 per cent for the week of Jan. 29 to Feb. 4, the lowest it's been since before Christmas. Ottawa's weekly rate of new cases per 100,000 population fell to 30.5 on Friday. Just two weeks prior, on Jan. 22, Ottawa's positivity rate was 3.2 per cent and the weekly per capita rate was 69.7 cases.
Graber said he's hopeful the ability to monitor COVID-19 variants could give public health officials an early warning about the possibility of community spread, if levels start to increase.
"We'll be doing this on a regular basis, testing for these variants. Whether it's daily or twice a week, we don't know yet, but hopefully we should be able to inform public health and give them that lead time to make decisions like more localized restrictions," he said.
You can find the data from the research project on its website.