Experts warn one rapid test may not be enough to detect COVID-19

COVID-19 rapid tests are the main way Manitobans are testing for COVID-19, but some experts are saying one test might not be enough.

Roger De Melo said he had COVID-19 symptoms on Friday, but the rapid test kept coming up negative.

‘’I thought you know it could be COVID but the fact that I was getting negatives - I'm going OK,” De Melo said in an interview with CTV News, adding he tested again the next day.

"By Saturday I started having a cough and by that time I thought no – that’s probably COVID.”

On Sunday, he did a third test which turned up positive.

University of Manitoba immunology professor Julie Lajoie said the first rapid test being taken might not test positive.

“The thing with Omicron now – they are going to be sick for one or two days, they are going to test negative so they think, 'OK – it’s another virus because there are a lot of other viruses in the air now,'” Lajoie said in an interview with CTV News. “But the thing now is we need to test a little more often.”

Epidemiologist Cynthia Carr, founder of EPI Research, said, “The challenge with rapid tests is that they are very different from the gold standard PCR that goes to the lab.”

Carr said how well rapid tests detect COVID-19 depends on the strain.

“With Omicron – the average is about 40 per cent. Four in 10 tests accurately identify properly that that person has the virus,” she said. “So certainly it should not be the only tool relied on and you should certainly do it more than once.”

Another challenge with the strains, Carr said, is how effective vaccines are and if treatments would work on it.

Lajoie said Omicron shows up more in the upper respiratory tract compared to previous strains. She said it is important to swab the throat, cheeks, and nose when testing.

‘’Rapid tests are super useful tools we just need to adjust how we use them with Omicron,” Lajoie said.

Lajoie said to test for COVID-19 every 24 hours for three days to be sure you are not COVID-19 positive.