Ontario should immediately expand its use of rapid COVID-19 tests if it hopes to slow the pandemic’s worsening third wave, say a variety of infectious disease and testing experts.
The rapid tests are said to be urgently needed in the province’s essential workplaces and schools, which largely remain open under the province’s new emergency brake shutdown.
“To my knowledge, we’re hardly using them at all,” Dr. Camille Lemieux, chief of family medicine at University Health Network and medical lead for the hospital’s COVID-19 assessment centre, said.
“We’re in a scenario right now where, if there ever was a time to use them, it is now.”
Rapid COVID-19 tests are less accurate and more susceptible to false positives than the lab-processed polymerase chain reaction (PCR) tests that have formed the backbone of Ontario’s COVID-19 testing strategy.
Ontario’s stock of rapid tests include PCR tests that do not have to be processed by a dedicated laboratory and antigen tests, which detect a protein that is part of the novel coronavirus.
Despite their drawbacks in accuracy and sensitivity, experts say rapid tests ultimately offer distinct advantages that could alter the trajectory of the pandemic if they are deployed widely and strategically.
Crucially, the tests can be used to catch people who are either asymptomatic or displaying only mild symptoms of the disease.
Ontario is already using some rapid tests for those purposes, but not to the extent that some say is needed to stymie the explosive growth of new cases that started in early March.
“The short answer is now. As soon as possible,” Dr. Kevin Schwartz, an infectious diseases physician at St. Joseph’s Heath Centre, said.
Schwartz co-authored a study on rapid tests published in the Canadian Medical Association Journal in March. His research found that testing only symptomatic patients is “slow and not sufficiently effective in preventing onward community transmission.”
“There’s a lot of tests that need to be acquired and need to be used,” Dr. Schwartz said of the need for more rapid tests.
Ontario has received 11 million rapid tests
Ontario’s stock of rapid COVID-19 tests are provided by the federal government, which has to date sent more than 11 million tests to the province.
In a statement to CBC Toronto, the provincial health ministry did not confirm how many of those tests it has used during the pandemic, or how many is has yet to distribute.
A spokesperson said the program has sent about 4.7 million antigen tests to at least 1,150 workplaces, though it is not clear how many of those have actually been used. The province said it is now sending “up to” 300,000 rapid tests per week to screen asymptomatic staff in sectors including manufacturing, warehousing and food processing.
“We are also deploying 385,000 tests weekly to long-term care homes and 118,000 weekly to retirement homes,” spokesperson David Jensen wrote in an email.
Essential workplaces most in need of rapid testing
Whatever remains in the province’s stock of rapid tests, experts say they should be immediately deployed to the locations now understood to be driving new infections.
“This is the biggest challenge we face now, be it in huge warehouses and other facilities,” said Sushanta Mitra, an engineering professor at the University of Waterloo who is developing a paper-based rapid test that can detect COVID-19 through saliva samples.© Robert Short/CBC These are examples of the rapid antigen test produced by the U.S. medical devices company Abbott. The test is one of four rapid tests available in Ontario.
Lemieux added: “The bulk of cases now that seem to be driving this pandemic are happening in workplaces where essential workers are unable to fully physically distance from one another.”
Mitra said results from rapid tests could enable governments to develop more proactive health measures before outbreaks occur. Mitra said those results could be used to “know exactly where we have to create interventions, where we have to be strategic in terms of vaccination, for example.”