Early on in the pandemic, Quebec was at the forefront of research into testing wastewater for SARS-CoV-2 as a way to track the progression of its spread.
The approach is now being used with increased frequency across North America, including in Ontario, to assist with the early detection of a rise in cases, spot neighbourhood outbreaks and prepare for an eventual rise in hospitalizations.
But funding for Quebec's pilot project ran out in December, just as the highly contagious Omicron variant was spreading rapidly among the population.
The province stopped making PCR tests available for the general population weeks later, on Jan. 5, after it was overwhelmed by the demand.
Experts say testing wastewater has the potential to be a useful tool to offset this lack of data.
"This method is really meant to complement existing systems," said Prativa Baral, an epidemiologist and doctoral candidate at the Johns Hopkins Bloomberg School of Public Health.
"But I think especially because our province doesn't have a rigorous testing capacity right now, this would be an excellent opportunity to get some pooled community-level data that would allow us to monitor our trends broadly."
Next Monday, Jan. 31, Quebec will further ease restrictions, citing a decline in hospitalizations in recent days.
At this point, however, experts say it will be difficult to quickly measure whether the change in policies has led to a resurgence in cases. A study released last week concluded that, for a period in December, there were five times as many cases as had been officially reported.
The general public is now being asked by the Quebec government to submit the results of their rapid tests to assist with tracking the pandemic.
COVID-19 hospitalizations in Quebec
Useful 'hand in hand'
Sarah Dorner, a professor at Polytechnique Montréal, began testing wastewater for SARS-CoV-2 in March 2020 as part of the province's pilot project. Her funding expired just as the Omicron variant began to widely in December.
Dorner said the technique — which is already used to detect other diseases, such as polio — has the potential to be a useful public health tool.
While wastewater data is not as precise as case counts, it can help understand the trajectory of disease in a community when PCR testing isn't available.
"I had always imagined that wastewater with rapid testing could be a really nice package as part of a solution for pandemic management," she said.
"We have rapid testing but now we don't have the wastewater. So it's unfortunate. It could really be useful hand in hand."
Dorner said testing wastewater could serve as an "early detector" not only in Montreal but in communities across the province.
"Going forward, it's really about setting up a sustainable monitoring infrastructure that could be used for this, but also other viruses in the future," she said.
WATCH | This expert says wastewater testing could help track Omicron:
In a statement, Quebec's Health Ministry said it was exploring how the technique could be used going forward, saying it could relate to "the rapid identification of new variants, using a specific analysis strategy."
"Analytical work to extend this approach across the province continues," said Robert Maranda, a spokesperson for the ministry.
The statement also pointed to a recent report by Quebec's public health institute, the INSPQ, which "highlighted the fact that this field is in its infancy and that more studies and experiments are needed to support its implementation."
Maranda said that public health departments at the regional level "wishing to do so can set up this surveillance."
A patchwork of projects
While Quebec may have reservations about its application, wastewater testing is increasingly common across the country in a context where clinical testing is overwhelmed, said Bernadette Conant, the CEO of the Canadian Water Network, which co-ordinates the COVID-19 Wastewater Coalition.
In Ontario, the province's science table, an independent advisory group, has begun making wastewater results public. The data shows a peak of virus concentration in wastewater around Jan. 4, then falling by about a quarter by Jan. 17.
Conant said the patchwork of systems set up across the country reflects the challenges of a co-ordinated response at the federal and provincial level.
She called it a "quintessential example of the challenges of the Canadian system."
WATCH | How wastewater testing works:
In Baral's view, while wastewater testing would be beneficial, she stressed Quebec should also take steps to prevent another shutdown, by putting in place improved ventilation in spaces known to be sites of transmission, such as schools and restaurants, and making our health-care system better prepared for a rise in hospitalizations.
"What I would love to see is a long-term plan from the government on how to deal with this moving forward," she said.