MONTREAL — Fifteen-minute COVID-19 tests have officially arrived in Quebec—meaning not just the physical tests, which arrived weeks ago, but the beginnings of a widespread campaign to use them across the province.
That could be a game-changer since it’s coming just in time for the province’s 18-day “pause,” beginning Christmas Day, experts say.
If combined with quick contact tracing, rapid COVID tests can actually shut down outbreaks before they start.
“From the time you’re contagious to the time that all of the people you might have infected are isolated is about 72 hours,” explains microbiologist Dr. Leighanne Parkes—or at least this is true if the patient arrives for the test right after symptoms appear, and if contract tracing happens fast.
In this scenario, the majority of the people you infected will be “latent,” meaning infected but not yet contagious. “So, these contacts are effectively stopped from going on and infecting others,” she said.
In other words, during a province-wide lockdown, if citizens cooperate by strictly staying home, the tests could help health authorities do a full-court press on the outbreaks that remain.
Dr. Matthew Oughton, an infectious disease specialist at McGill University, said that to take good advantage of a circuit-breaker like the one Quebec is about to begin, “you also launch wide-scale rapid testing.”
RAPID TESTS TO GO TO WORKPLACES, ‘MARGINALIZED’ PATIENTS, OTHERS
While slow to adopt rapid testing, which arrived in many places across Canada through the fall, Quebec now has 1.3 million rapid tests at hand, and, equally importantly, it’s largely learned how to use them.
The first rapid tests were used Dec. 7 in Quebec City, the province says, and the experimentation moved onto a bigger scale last week.
“Deployments have been underway since last week in the Saguenay-Lac-Saint-Jean and Chaudière-Appalaches regions,” a health ministry spokesperson wrote in a statement to CTV News Wednesday.
“Several other deployment projects are planned in most other regions.”
There are two kind of tests, both of which use nasal samples and neither of which requires a lab.
One type of test comes with a bulky but portable device that the samples can be plugged into, sort of like a mini-lab, returning a result immediately.
The province has 219 of those portable devices to parcel out, and 101,376 of the tests, called ID NOW. They will be “rolled out gradually” in remote regions, among other places, the province wrote.
The ID NOW tests will go to “regions where [COVID-testing lab devices] are difficult to access; for example, a server laboratory located two hours away.”
They’ll also be given to “teams dedicated to [outbreak] investigations in order to use them quickly with health-care workers and [patients or residents] during the early symptoms,” and they’ll take pressure off regular labs when they’re overloaded.
A second type of test uses antigens to detect the virus, turning the nasal sample into a liquid that can be dripped onto a strip, a bit like a pregnancy test. They’re more portable than the other kind of test and are called PANBIO and BD Veritor.
Quebec has 1.2 million PANBIO tests. Its plan is to use them “with marginalized and socially disrupted clienteles who do not use the resources of the health and social services network,” said the statement.
The strips will also be used “during major outbreaks in the workplace” and, again, to handle excess demand when labs are overloaded.
SAME-DAY CONTACT TRACING IS POSSIBLE
One worry with the rapid tests is that they’re not as accurate as the lab-based tests, which creates a serious risk: people who get a false negative can have false confidence, going out and infecting even more people.
“Remember that in the event of a negative result, isolation is still necessary,” the province cautioned.
This is also why the province is limiting their use. Because the rapid tests are less accurate than the regular ones, “deployment must be carried out in a very supervised and coordinated manner,” the province wrote.
“To this end, an expert committee has been set up to determine the populations and environments to target for the use of these less sensitive rapid tests.”
But many public health experts have said that shortcoming is balanced by the advantages of speed, considering the rapid tests still catch many positive cases, including the most contagious ones.
In the normal system, picture a situation where “patient zero presents for testing on the day their symptoms start, and it takes seven days from the time the test is done to get their results,” Dr. Parkes explained (though in many parts of Quebec, positive results are coming back much more quickly than this).
When the test comes back, imagine waiting another two days to be called by contact tracers, she said. Those extra few days have created many more contacts, who in turn have also transmitted to others, who have transmitted to others.
Public health officials in this hypothetical but all-too-common scenario are now “behind three generations of cases, and depending on how ‘naughty’ these contacts have been in the past 11 days, they might have infected a sizeable group of people,” Parkes said.
Rapid tests mean that contact tracing can be done on the spot: if a person hears 15 minutes later that they’re positive, they can be asked immediately about their recent contacts.
If those people are all called immediately to get their own test the next day, and to self-isolate, the group has effectively cut off the outbreak at the first generation of contacts.
ZEROING IN ON TROUBLE SPOTS
Ideally, people who get negative rapid results should stay wary and remain isolated until they can get a slower test with a more reliable result, Dr. Parkes warned.
But “in the end, rapid testing has a role, particularly in certain populations and situations,” she said.
Dr. Oughton said going into the Christmas season that in much of Canada, “essentially, we’re flying blind or close to it.”
Somewhere around two-thirds of COVID-19 infections picked up in the community “have no established epidemiological links,” he said—contact tracers never learn where they came from.
“If you just don’t have that information, how are you supposed to intelligently target your transmissions?” he said.
“You don’t necessarily know… where you can intervene early, identify those people, get them quarantined early.”
Despite the province saying it’s ready to deploy in most regions, it didn’t respond to a question about whether it planned to use rapid testing in a concerted way during the lockdown.
GARGLE TESTS ALSO TO BE DEPLOYED
The province said a third kind of new test is also in play: gargle and saliva tests, which aren’t rapid but can help test patients for whom the nasal swabs are difficult, or who need to do the tests at home.
Saliva tests have been used since August, while the gargle tests have been used since November 4 in Chaudière-Appalaches and since November 26 in Saguenay–Lac-Saint-Jean, the province wrote.
These tests are quite accurate based on one study done so far in Quebec, but the province wants to take more time to check their performance and to make sure they can be used in a standardized way, it wrote.
Still, it’s “considering a gradual deployment for sampling by gargling as soon as possible.”