Every Quebecer is entitled to five rapid screening tests per 30 days. What to do with this precious kit? Answers from three experts.
When to use the tests?
The Quebec government recommends them when a person presents symptoms similar to COVID-19. “In the absence of symptoms, rapid tests should not be used, writes Quebec in its guide on the Internet. Exceptionally, before visiting a very vulnerable person, it is recommended to do a quick test. “
According to the experts consulted, asymptomatic people should also resort to rapid screening tests.
The DD Caroline Quach-Thanh, microbiologist-infectious disease specialist at the Sainte-Justine University Hospital Center, advises people to use them “just before going to a gathering”, for example an hour before a family dinner. “It can detect asymptomatic excretors that have a high viral load,” she explains. She says people with COVID-19 can be contagious two days before symptoms appear. “At that point, the viral load is very high,” she continues.
Nathalie Grandvaux, director of the CHUM’s laboratory for research on the host’s response to viral infections, reminds us that the test must be repeated each time we attend a gathering.
But why does Quebec recommend them only when visiting “a very vulnerable person”? “In fact, what they tell us is that there are not enough tests for everyone to do everything everything, all the time, answers the D.D Quach-Thanh. But if you got it because the school gave you it, the office gave it to you, or because you bought it, well, you can do it. “
If our number of tests is limited, we use them at gatherings where there are vulnerable people, such as newborns or the elderly, says DD Quach-Thanh.
How effective are they?
Tests detect 80 to 90% of symptomatic people who are infected, according to Dr André Veillette, immunologist at the Montreal Clinical Research Institute. “Yeah, maybe 10% of people are going to be missed, but if we miss them, well, it’s people who are probably less infectious. Anyway, adds the doctor, people who have symptoms should not take part in gatherings. “If it’s the cold or the flu, you also have to be responsible and manage not to give it to others,” he emphasizes.
For asymptomatic people, tests detect 40% of people with COVID-19, according to DD Quach-Thanh. This rate of effectiveness dates back to the days of the first strain of COVID-19. “We have the impression that with the Delta and Omicron variants, the viral load being higher, it is possible that it is better than that,” she adds.