Experts say rapid antigen testing is emerging as an important tool as Canada’s pandemic strategy shifts from public health vigilance to an emphasis on personal responsibility.
However, they warn that the results of rapid tests should be read carefully due to limitations in diagnostic accuracy and precision.
A professor of biomedical engineering and immunology at the University of Toronto says rapid testing is an easy and convenient way to help Canadians make better choices about their own health and the safety of others.
However, Omar Khan says rapid tests work best when combined with public oversight strategies that can track the spread of variants to help update health policy.
Dr Christopher Labos, a Montreal-based cardiologist with a degree in epidemiology, says more than one quick test is needed to rule out infection due to high rates of false-negatives.
Labos says possible sources of error include improper technique, early detection of the disease for detectable virus levels, and preliminary data suggesting that rapid trials are less sensitive to the Omicron variant.
In February, the Ontario Scientific Advisory Board COVID-19 published findings from an analysis of preprint studies suggesting that the cumulative sensitivity of rapid antigen tests to detect Omicron infections is about 37 percent, with a percentage of about 37 percent.
Health Canada says on its website that it has “no evidence” that the variants affect the ability of testing-approved trials to confirm COVID-19 cases, but notes that these new devices are still under investigation.
“Now that we are in the ‘judge your risk’ phase of the pandemic … I think people need to realize that the risk of false negatives with rapid tests is very real,” Lambos said, noting that the data indicate the percentage. of false positives is quite low.
“If you consider your negative result as permission to return to normal, you may inadvertently infect other people, so I would continue to isolate myself, repeat the test and make sure you do not have COVID.”
Ontarians aged 60 and over can book an appointment for a fourth dose of COVID-19 vaccine on Thursday.
First Nations, Inuit and Métis individuals and non-indigenous household members aged 18 and over can also start booking these shots on Thursday.
The fourth installments are offered within a recommended period of five months after the initial booster dose.
This Canadian Press report was first published on April 7, 2022.
