Opinion

After getting over our obsession with hoarding toilet paper, it appears we’ve shifted attention to hoarding rapid antigen tests.

After getting over our obsession with hoarding toilet paper, it appears we’ve shifted attention to hoarding rapid antigen tests.

There are so many people trying to get tested, most provinces including Manitoba are severely restricting access to the lab-based polymerase chain reaction (PCR) tests. Instead, the provinces are offering rapid antigen tests so that anyone with symptoms who does not need hospitalization knows if they need to quarantine.

Demand for rapid tests rises, even among symptom-free

People walk out of the U of M COVID-19 testing site in Winnipeg with rapid tests.
People walk out of the U of M COVID-19 testing site in Winnipeg with rapid tests.

Posted: 7:00 PM Jan. 6, 2022

Soaring COVID-19 case counts prompted healthy Manitobans to get in long lineups for free packages of rapid tests, a day after the province announced a change to its testing policy.

With the wind driving temperatures down to -30 C, Cory Werenich decided to brave the cold for a zipper lock bag containing three rapid tests from the provincial test site at the University of Manitoba, despite not having symptoms of COVID-19.

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The mere suggestion of free tests inspired many Canadians to rush out and start building their personal stockpiles. In Ontario, for example, free government rapid tests have been re-sold online for ridiculously inflated prices.

Although that has not happened here, yet, the lure of free rapid tests was enough to lure hundreds of Manitobans out into the frigid Arctic air enveloping Manitoba.

A Free Press story quoted a variety of people lined up at a University of Manitoba testing site Thursday to get a plastic bag with three rapid tests. Some admitted they did not actually meet provincial criteria for obtaining the tests: they had not been exposed to a confirmed case of COVID-19 and were not symptomatic.

They just liked the idea of having the tests, just in case.

"If you ever feel ill in the morning," one man said, "we just figured we have them on hand just before we go out and contaminate someone else."

Comments like that suggest some of us may be operating under a profound misunderstanding about the value of these tests.

First, some valuable, technical background.

Normally, a PCR test is the most accurate way of determining whether someone is infected with the novel coronavirus. Not foolproof, but very close. However, PCR tests are somewhat expensive, time-consuming and must be done in a laboratory setting.

A PCR test is the most accurate way of determining whether someone is infected with the novel coronavirus but the tests are somewhat expensive, time-consuming and must be done in a laboratory setting.

TRIBUNE MEDIA TNS

A PCR test is the most accurate way of determining whether someone is infected with the novel coronavirus but the tests are somewhat expensive, time-consuming and must be done in a laboratory setting.

Rapid antigen tests are popular because they can be self-administered and produce results in less than an hour. For anyone who believes they may have contracted the virus, rapid tests can provide very valuable information.

However, the speed offered by a rapid test comes largely at the expense of accuracy.

Rapid antigen tests, or lateral flow tests as they are sometimes called, are rated both on sensitivity (the ability to detect small amounts of virus) and specificity (the ability to identify the coronavirus as opposed to other contaminants). There are many different brands of rapid tests, with dramatically different performance on both parameters.

A March 2021 meta-analysis published in the British Medical Journal looked at 64 different studies involving multiple brands of rapid antigen tests. It found that for symptomatic people, the tests were on average about 72 per cent accurate, ranging from 34 per cent to nearly 90 per cent, depending on the brand.

To be clear, the province has done a good job of explaining that rapid tests should only be used when symptomatic, or if they have been exposed to a confirmed case of COVID–19.They should not be used as an instant ‘get–out–of–COVID–jail–free’ card, or as some form of protection before engaging in risky activity.

However, with asymptomatic people, the tests were only accurate about half the time. That is why most epidemiologists recommend rapid tests only be used in the earliest stages of symptoms, when viral loads are higher and thus the results are more accurate.

The point here is that rapid antigen testing was never supposed to serve as our primary COVID-19 screening tool. They are designed to be used as part of a broader screening protocol that ultimately funnels people with symptoms and higher risks of complications to PCR testing.

A good example is professional sports. Most leagues require players to do multiple rapid tests each week. If someone tests positive, they are put into "protocol" and isolated. They are then given a PCR test to confirm the rapid test results. Sometimes, they must produce multiple negative PCR results over several days before they are allowed to rejoin their teams.

COVID-19 rapid antigen tests are popular because they can be self-administered and produce results in less than an hour.

THE CANADIAN PRESS/JEFF MCINTOSH

COVID-19 rapid antigen tests are popular because they can be self-administered and produce results in less than an hour.

None of the athletes would be freed from protocol solely on the basis of rapid test results.

Obviously, a provincial government cannot afford to provide that level of testing to the general public, particularly at a time when the variant driving the outbreak is as contagious as Omicron. However, what government can do is make sure people are only using the rapid tests for the purpose for which they were intended.

To be clear, the province has done a good job of explaining that rapid tests should only be used when symptomatic, or if they have been exposed to a confirmed case of COVID-19.They should not be used as an instant ‘get-out-of-COVID-jail-free’ card, or as some form of protection before engaging in risky activity.

These tests cannot tell you with any certainty if you are safe to attend a large household gathering, attend an in-person church service, visit an elderly parent or eat in a restaurant. And you should not use them after attending a large house party or an NHL hockey game to see if you are virus-free.

These tests cannot do those things.

And remember, the prescriptive action is the same whether you get a positive or negative result: isolate at home for at least five days.

Rapid antigen tests can be a valuable tool in the pandemic response. But we all have to make sure we don’t rush to hoard them on the mistaken belief that they are definitive.

Rapid tests cannot, on their own, free us from pandemic hell. But if they are misused, they could prolong our stay there.

dan.lett@winnipegfreepress.com

Dan Lett

Dan Lett
Columnist

Born and raised in and around Toronto, Dan Lett came to Winnipeg in 1986, less than a year out of journalism school with a lifelong dream to be a newspaper reporter.