Rapid tests a 'good additional tool' but not a replacement for PCR tests, expert says

Amid concern over spread of the new Omicron COVID-19 variant in Canada, calls are growing for rapid antigen tests to be made more accessible, and to be used in more settings.

However, virologist Jason Kindrachuk says, while the tests are a “good tool,” they shouldn’t be seen as a replacement for the widely used polymerase chain reaction (PCR) tests.

PCR tests are still considered the “gold standard” in Canada. But, because the samples from PRC tests must be sent to laboratories for processing, it can take a few days to receive results.

Kindrachuk, an assistant professor at the University of Manitoba who serves as the deputy of the coronavirus variants rapid response networks tier 2 focussing on molecular pathogenesis, told CTV News Channel that rapid antigen tests – which can provide on the spot results in around 20 minutes, are a good tool to have because they’re able to identify COVID-19 cases quickly.

“Certainly in those communities right now where there isn’t really any vaccine protection – certainly in younger age groups and in schools [where] we have concerns in regards to transmission – we need to be able to identify those cases very quickly,” he said Thursday.

But, Kindrachuk said the new Omicron variant, first detected in South Africa, “throws a bit of a wrinkle at us.”

“We have to ensure that certainly all these rapid tests will still identify the Omicron variant,” he said. “But we have to appreciate that the Delta [variant] is still circulating widely, and we need to be able to try and cut transmission chains as quickly as we can.”

Kindrachuk said early data out of Europe suggests that the majority of the rapid antigen tests have so far been able to detect the Omicron variant.

“We want to ensure that those are all validated, but that gives us an additional leg-up without having to produce new products to get out to market,” he explained.

Kindrachuk said, when they are used in combination, rapid antigen tests and PCR tests give Canada “an advantage.”

He said PCR tests are “highly sensitive” to the coronavirus, and can help determine which variants are spreading across the country.

They also help to give a “better indication of whether or not we’re seeing say something like asymptomatic infection, as compared to the rapid test.”

“But a rapid test give us a very, very good additional tool to be able to do that on-site screening and then still be able to follow-up with other testing,” Kindrachuk said.

HOW MANY RAPID TESTS HAS CANADA ORDERED?

Data released by the federal government says that, as of Nov. 30, a total of 94,648,718 rapid antigen tests had been received by the country. Of those, a total of 79,746,088 had been shipped to the provinces and territories.

The data suggests that, as of Nov. 26, of the tests shipped to the provinces and territories, 58,082,137 had been distributed to the final point-of-care setting where they would be administered to a patient.

The government says, to date, 14,759,881 rapid tests have been reported as used.

TESTS SITTING ON SHELVES IN ONTARIO

Across the country, provinces have taken a number of differnt approaches when it comes to the rollout of rapid antigen tests. However, they have mostly been used in high-risk settings such as long-term care homes, other congregate living situations with seniors, or at schools and businesses.

Some people, though, are calling for a more widespread use of the tests, as some provinces face a surge in cases.

One Ontario pharmacist, Kristen Watt, says the rules need to be reassessed.

In a tweet on Saturday, Watt said at her pharmacy, rapid tests sitting on the shelf are set to expire in February.

“They were supplied to us by the federal government,” she told CTV News Channel on Tuesday. “I know they were purchase early on, they made it to pharmacies in the summertime.”

However, Watts said the only way the tests can be used is if they’re supplied to businesses who have applied and received an approval number.

“Unfortunately, I have no way to provide these directly to people who are not part of a business,” she said. “And I think it would be a great way to help curb the spread during holiday season.”

Watts said in the “ideal situation,” she could bill tests to a person’s health card, so there would be “no charge to the patient.”

“If we could bill these tests through health cards, maybe once a week a family could acquire a certain amount of tests in a period of time,” she said. “It would definitely help us understand the rates of community spread and keep people safer during the holidays.”

What’s more, Watts said at her pharmacy, she’s had an increase in demand for the rapid tests, saying they get questions “every day” from people looking to get their hands on a test for personal use.

“Unfortunately, the tests that we have in pharmacies and not just these federally supplied tests, but all the tests that we have in pharmacies right now are only approved for use at point-of-care testing, which means that a healthcare worker, specifically in this case pharmacists, pharmacy students, pharmacy technicians, must be part of the administration of the test,” Watts said.

“We need a bit of a shift in our mentality to approve these for self use,” she said. “And then a move by the province to allow us to distribute them in that way.”

Currently in Ontario, those looking to get a rapid test could face a bill of around $40, a price that Watt said is not accessible for many.

Kyro Maseh is a pharmacist and the owner of Lawlor Pharmacy in Toronto.

He told CTV’s Your Morning on Friday that he has been advocating for the wide use of rapid antigen tests for more thana year.

Maseh said the tests are “extremely effective at catching the COVID virus early.”

“But at the end of the day, it doesn’t really matter if the general public is not able to access these tests in a very timely fashion, then they lose their significance as a screening tool,” he said.

Maseh said the tests need to be “accessible with no barriers” for all Canadians.

“If there is any sort of confusion or any sort of barrier in providing these tests, then that’s a failure, plain and simple.” he said.

VOLUNTARY SCREEN TESTING

On Thursday, the Ontario Science Table released a report recommending rapid antigen tests be used for voluntary screen testing.

The advisory table pointed specifically to schools, saying in areas where there are 35 or more weekly cases per 100,000 people, elementary students should be tested using rapid antigen tests once a week.

Dr. Fahad Razak is a member of the Ontario Science Table, and is an internal medicine physician at St. Michaels Hospital.

He told CTV News Channel that rapid antigen tests have an “important role” in this point in the pandemic.

“The evaluation that we did was based on the Delta variant, which is extremely infectious,” he said. “We know Omicron is probably even more infectious than Delta.”

He said the evaluation suggests that the rapid antigen tests are “very effective” at screening asymptomatic individuals for the current version of the COVID-19 virus that is circulating.

“So this is a situation for example, in a school where you want to do regular surveillance, and they're really important to prevent wider outbreaks from occurring,” he said.

Razak said the accuracy of the rapid antigen tests depends on the characteristic of the virus.

He said as the virus becomes more infectious, the tests actually work better.

However, Razak emphasized that the rapid antigen tests should be used for surveillance in asymptomatic people.

“This is for surveillance in a population where you're starting to get an increased spread, and you want to prevent those outbreaks from occurring,” he said. “And with Delta, these tests seem to work extremely well in that kind of application.”

Razak said if you have COVID-19 symptoms you will still need to get a PCR test at a testing centre. 

With a file from CTV's Chris Herhalt