Relying on a rapid COVID-19 test? Double check results: Sask. epidemiologist

Following the Saskatchewan government's announcement that the province would be relying more on take-home rapid testing kits to detect COVID-19 cases, an epidemiologist recommends double-checking test results.

"Take two tests and hope they are both negative, I would actually space that about 24 hours apart," said Dr. Nazeem Muhajarine.

The province announced Thursday asymptomatic residents who test positive for COVID-19 on a rapid test will no longer be required to receive a PCR test to confirm, along with changes to isolation requirements.

"People are using them, I'm thankful for that, I'm thankful for that because they're identifying COVID quicker and they're breaking that transmission cycle ultimately quicker," said Premier Scott Moe.

“By the time you do a PCR test and you get in touch with contacts, those who were exposed are already transmitting within two to three days," said Dr. Saqib Shahab, the province's chief medical health officer.

The move is also expected to reduce pressure on the province's ability to process PCR tests as case counts increase amid the rise of the Omicron variant.

But Muhajarine said the rapid tests are not foolproof. He said they have primarily been used as a screening tool up until this point and cited a recent study out of Denmark showing the test can present a false negative result as much as 50 per cent of the time.

"Every one out of two negative tests could be a false negative," Muhajarine said. "Meaning that it is erroneously signalling that somebody is clear."

Along with double checking negative results, Muhajarine said Omicron is most likely to present the highest viral load within the first two to three days. That means a rapid test is most likely to pick up a positive during that window.

Despite the potential shortcomings posed by rapid tests, Muhajarine applauds the province on making them readily available and encourages residents to keep them handy.

But he cautioned not requiring a PCR test to confirm positive results is going to make it increasingly difficult to keep track of case counts and could also present problems in the future for potential long-haulers.