Experts argue that rapid antigen tests are becoming an important tool as Canada’s pandemic strategy shifts its focus to individual responsibility.
Experts caution, however, that the results of rapid tests should be viewed with caution due to limitations in diagnostic accuracy and precision.
A professor of biomedical engineering and immunology at the University of Toronto, Omar Khan, believes rapid tests are a simple and convenient way to help Canadians make better choices about their health and the safety of others.
But he also says rapid tests work best when paired with public surveillance strategies that can track the spread of variants to inform health policy.
Another test after a negative
Dr. Christopher Labos, a Montreal cardiologist with a degree in epidemiology, believes it takes more than a rapid test to rule out an infection due to high rates of false negatives.
He says potential sources of error include improper technique, tests used too early in the disease for viral levels to be detectable, and preliminary data suggesting that rapid tests are less sensitive to the Omicron variant.
In February, Ontario’s COVID-19 Science Advisory Table released the results of an analysis of pre-published studies suggesting that the combined sensitivity of rapid antigen tests for detecting Omicron infections is approximately 37%, against 81% for the Delta variant.
Health Canada says on its website that it has “no evidence” that the variants affect the ability of agency-approved tests to confirm cases of COVID-19, but notes that these new devices are still under review. of an investigation.
“Now that we’re in the ‘judge your own risk’ phase of the pandemic, I think people need to realize that the risk of false negatives with rapid tests is very real,” Labos said, noting that evidence suggests that the false positive rate is quite low.
“If you take your negative result as permission to go back to normal, you could inadvertently infect other people, so I will continue to isolate myself, repeat the tests and make sure you do not have any COVID. »
More than 76,000 appointments were made for a fourth dose of the COVID-19 vaccine on Wednesday, the first day that people aged 70 and over had access to it. People aged 60 and over will in turn be able to make an appointment starting Monday, April 11.
It is recommended to respect a minimum interval of three months between the first and the second booster dose.