New guidance: Swab your mouth and nose for more 'complete' COVID-19 rapid test result

As cases of COVID-19 are on the rise again in Quebec, public health officials issued new guidance for rapid COVID-19 tests Friday in a bid to lower the rate of false negatives.

Rapid antigen testing remains the only option for most Quebecers amid a new surge of coronavirus infections since the province cut off PCR testing to the general public in January.

Dr. Luc Boileau, the province's interim public health director, said during a virtual news conference Friday it's now recommended to pass the swab in the mouth along the cheeks and the back of the throat as well as inside the nostrils. It's recommended to do the swab in the mouth before the nose.

Boileau said the new method provides a more accurate and "complete test." Studies have shown that swabbing the mouth and throat can produce fewer false-negatives.

Dr. Jean Longtin, a microbiologist and expert in management of the pandemic at Quebec’s Ministry of Health and Social Services, explained that swabbing both locations “increases the sensitivity of the tests."

A study from Dalhousie University published in preprint form on Medrxiv at the end of January showed that the rate of false negatives decreased from 22 per cent to 5 per cent when the throat is swabbed first followed by the nose, instead of swabbing only the nose.

"It all kind of fits as well with some research about Omicron and that it has better affinity for throat tissue, more so than other variants, and potentially may appear in the throat sooner than in the nose," said medical microbiologist Dr. Glenn Patriquin, who authored the study. 

"It fits with people’s new complaints of sore throat especially with Omicron."

Dr. Patriquin said he supports the new recommendation from Quebec since it would "increase the performance of the rapid antigen test."

"So I would think they’re [Quebec] likely to detect more cases with this recommendation."

The health ministry published an instructional video Friday explaining how to perform an oral nad nasal swab. 

Ontario's science table noted in a brief from February that a study found sensitivity for the Omicron variant from just a nasal swab was about 68 per cent, while sensitivity for both the nose and mouth swabs rose to 82 per cent.

On Friday, Quebec recorded an additional 55 COVID-19 hospitalizations as well as 3,572 new infections. Another 30 deaths were also added.

Hospitalizations and daily cases have been rising in recent weeks. Last week, Dr. Boileau said the true number of daily infections is likely up to 10 times higher than the official tally.

Quebec has extended access to free rapid testing kits at select pharmacies across the province. Each Quebecer is eligible every 30 days to get a free rapid testing kit, which contains five tests. 

DON'T SKIP THE THIRD DOSE: BOILEAU

Even though cases are rising and hospitalizations surpassed the 1,600 mark on Friday, there are no plans to introduce new public health measures, Boileau said. Earlier this week, the province extended its face mask mandate to the end of April -- two weeks longer than previously scheduled.

The progression of the sixth wave is concerning to public health, with the number of health-care workers away due to COVID-19 at 13,000. "It's a lot," the interim public health director told reporters. 

He also renewed his plea for Quebecers to avoid socializing if they have symptoms, to exercise caution with older people who are more vulnerable to serious infection -- especially during the upcoming Easter holiday -- and to not skip the third dose, even if they were recently infected with Omicron in the last few months.

Each day there are about 1,500 to 2,000 people who get their booster shot, but Boileau said that's "not enough."

"A lot of them have been infected by Omicron recently in the last three months so they argue that, 'Well, if I have Omicron, it's like a third dose,' which is fair … But after three months, we seriously recommend it to benefit from their third dose to upgrade their immune system," he said.

"We observed that there's a lot that might be reluctant … but we hope that this message will get through."

Dr. Marie-France Raynault, a senior strategic medical advisor to public health, also said during Friday's update that despite the rise in cases, there are no plans to reintroduce new health measures in schools.

"The situation is not worse in school. In fact, it's a little bit better than what we see elsewhere. If we compare ourselves with the other provinces we see that we're one of the provinces with [Prince Edward Island] where the measures in school are the most strict because the masks are still present in school except when the children are sitting in class. So we follow closely the situation," Dr. Raynault said.