Latest research says combination of throat and nose swabs provides better COVID-19 rapid test results: Nova Scotia Health

In a Canadian first, Nova Scotia researchers say COVID-19 rapid tests that include both throat and nose swabs provide greater accuracy in detecting the virus.

Up until now, the instructions provided by the manufacture has been for nasal swab only.

Now, based on research led by Nova Scotia Health's microbiology team, public health is recommending Nova Scotians using rapid tests swab both their throat and nose when collecting their sample.

In a release Friday, Nova Scotia Health said its working to update the current testing instructions that people receive when they pick up a rapid test.

The research was prompted by public discussion theorizing that a combined sample may produce more accurate results.

Speaking to CTV Thursday, Dr. Todd Hatchette, the chief of the province’s Division of Microbiology, Department of Pathology and Laboratory Medicine, said researchers found using a single swab on a person’s throat first, and then in both nostrils is more effective at detecting Omicron than doing either site alone.

“When we tested just over 1,500 people, we found that either the nose or the throat both detected about 60 per cent of people, but if you did a combined nose / throat, it detected over 82 per cent of people,” said Hatchette.

The research started about a week ago. Officials at the microbiology lab worked with volunteers at the Halifax Convention Centre testing site to collect the data.

In Friday’s release, Nova Scotia Health says collaboration with volunteer-based community rapid testing sites was key to the project’s success and allowed the project to rapidly answer a question that many jurisdictions across the country have been asking.

The investigation compared results of a common rapid take-home test using three sample sites: nasal swab; throat swab and; combined nasal/throat, the release said. All results were confirmed with PCR testing. Compared to PCR test results, samples from nasal or throat swabs each detected 64.5 per cent of cases; however, combining the nose and throat swabs increased sensitivity to 88.7 per cent.

This research project has been submitted for publication.

Dr. Theresa Tam, Canada's chief public health officer, speaking Friday from Ottawa, welcomed the Nova Scotia swab study.

“I’ve asked our laboratory network, our laboratory experts, to take that into account and see whether we can provide some sort of guidance,” Tam said. “But, of course, I think we’ve been discovering that the Omicron variant may be behaving a bit differently to the previous variants, so this approach, this swabbing, might be useful.”

One thing to note, public health is advising that if only one location of the sample is being used, it should be the nasal swab, as the throat swab alone is not as effective as the nasal swab.

Nova Scotia is the first to report research results supporting a combined throat/nose collection method for self-administered rapid antigen tests.