P.E.I.'s new rapid test guidance to include option to swab both nose and throat
Jessica Doria-Brown | CBC News | Posted: February 11, 2022 10:00 AM | Last Updated: February 11, 2022
Study out of N.S. says this increases detection of Omicron variant of COVID-19
The Chief Public Health Office is making plans to update its guidance on rapid testing to include the option to swab both your throat and nose.
It's a change in recommendation that Nova Scotia Health made last month, after research showed nasal or throat swabs on their own detected 64.5 per cent of cases. But combined swabbing of the nose and throat increased the test sensitivity to 88.7 per cent. PCR tests were used to confirm those results.
Dr. Todd Hatchette, head of Nova Scotia Health's microbiology team and a professor in Dalhousie University's department of pathology and laboratory medicine, led the research.
"There were lots of anecdotal reports of people saying that the nose swab using rapid antigen test was not picking up cases and when they swab their throat, it was," said Hatchette.
"But there was no real rigorous data to try and support that claim, so we went out and tried to prove or disprove whether that was the case."
Testing was conducted in community settings, with nearly 1,500 asymptomatic individuals.
Why more effective?
He said it's not yet clear why swabbing both the throat and the nose is a more effective way to detect COVID-19.
"There is some data to suggest that perhaps Omicron likes to grow initially in a different place, so maybe it likes the back of your throat more so than the front of your nose, and maybe it takes time to transition to that area of your respiratory tract," said Hatchette.
"No one's really sure at this point, but it does offer an opportunity to increase your rate of detection if you combine."
He said the efficacy of swabbing both the throat and the nose hasn't yet been tested on symptomatic individuals, but he suspects there would be an increase in their COVID-19 detection rates as well. He said when it comes to PCR tests, adding the throat swab doesn't appear to increase detection.
"We did this same project looking at our PCR tests. Again, the question is: if we saw this difference using antigen tests, would we see the same with PCR tests?" said Hatchette.
"So it was slightly different in that we compared a throat/nose combination with the deeper nasopharyngeal swab. And in that circumstance, we didn't find any significant difference between the two, suggesting that both swabs … can be continued to use to detect Omicron."
Officials with P.E.I.'s Chief Public Health Office said these findings have been a topic of discussion this week and confirm rapid test guidance in this province will soon be updated to include the combination throat/nose swab option, which they say increases the sensitivity of the test.
"It is important to note it is not a throat or a nasal swab, but rather a nasal or a combined throat and nasal," said an official, adding more details on this new guidance will be shared next week.