Quebec avoids relying on rapid COVID-19 tests as pressure mounts to follow Ontario's lead

Health officials in Quebec remain wary about deploying rapid antigen COVID-19 tests on a large scale and suggested Monday that jurisdictions who adopt that approach, such as Ontario, will face huge numbers of inaccurate results.

At the same time, Quebec government experts said they are ready to increase use a different type of rapid test following successful pilot projects in the province.

"We've been very cautious about implementing and distributing rapid tests in Quebec, but we are pretty confident about the ID NOW," said Dr. Isabelle Goupil-Sormany, a Health Ministry advisor, referring to the trade name of the test. 

ID NOW tests, which are made by the American multinational Abbott Laboratories, are similar to the current COVID-19 test widely available in Quebec. Both rely on a polymerase chain reaction (PCR) to detect the virus.

But while the ID NOW test can deliver reliable results in as little as 15 minutes, each kit can only process four at a time, and Quebec only has enough supply to conduct 190,000 more tests.

Rapid tests that look for antigen molecules specific to COVID-19 are available in greater numbers in Canada and are easier to use. But they are also less sensitive than PCR-based tests and can produce high rates of false negatives.

Some independent medical experts have suggested that using antigen tests more widely, and more often, would more than compensate for their lower reliability. Antigen tests, they argue, have well-documented success in identifying contagious coronavirus carriers.

Along with opposition parties in the province, those experts have been pushing the government to give a greater role to rapid antigen tests in its overall testing strategy.

"More and more countries and provinces will want rapid tests and soon the demand will be so big that there will be production limits. The day Quebec changes its mind we won't be able to get any because we didn't plan ahead," said David Juncker, a professor of biomedical engineering at McGill University.

Mounting pressure to use more rapid tests

On Monday, officials in Ontario said the province will soon have the capacity to conduct 25,000 antigen tests weekly as part of its effort to return students to class following extended school closures.

The province has already ordered 9 million antigen tests, whereas Quebec has ordered only 2 million (in addition to the 1 million it has on hand).

Under pressure to follow Ontario's lead, the Quebec government organized a technical briefing Monday to defend its approach in front of journalists and opposition politicians.

Experts on the call said their research showed that 50 per cent of antigen tests produced false positives, and around 33 per cent produced false negatives. That makes it an unreliable public health tool, they said, for screening asymptomatic populations.

The conventional PCR test is much more reliable and Quebec labs can now usually produce results within 24 hours, said Marie-Eve Bédard, a senior official in the Health Ministry.

Labs in Ontario, on the other hand, have struggled to deliver results as quickly, she said. Rapid tests allow the province to speed up testing, but that comes at a cost.

"Ontario has voluntarily accepted to miss more cases. We think they could miss one out of two, maybe even two out three cases. So it's a different strategy," added Goupil-Sormany.

Guidelines coming for workplaces

While health officials in Quebec will avoid using antigen tests to screen out unsuspecting carriers of the disease, they did acknowledge the tests can be useful in certain situations.

Goupil-Sormany provided the example of a suspected outbreak at a workplace, where a handful of workers had already tested positive via the PCR method. The antigen test would permit officials to quickly establish whether the virus had spread to others.

Several large employers in Quebec, including Hydro-Québec, Rio Tinto and Air Canada, have purchased antigen tests. Heath Ministry officials said they would provide guidelines to companies on how best to use the tests.

Given the possibility of misleading results, Goupil-Sormany said there is a concern they generate a false sense of security.

The ID NOW tests, on the other hand, are set to play a more active role in government efforts to contain transmission.

Already in parts of Montreal, symptomatic students who are sent for tests are given the ID NOW version. The hope is with quicker results, school administrators can shut classrooms before the infection spreads.

The ID NOW tests are also being used in mobile clinics that have been dispatched to Montreal neighbourhoods with high infections rates.

"People get results on site within two hours," said Goupil-Sormany. "It allows us to reach out to these populations and offer them rapid tests."