UArizona examining new saltwater mouthwash COVID-19 test

PHOENIX — The University of Arizona is examining a new method of COVID-19 testing that uses saltwater mouthwash instead of nasal swabs.

The test was devised by Michael Worobey, who serves as the head of the university’s Department of Ecology and Evolutionary Biology.

Worobey said the mouthwash test differs from other saliva-based versions such as the antigen and polymerase chain reaction (or PCR) tests in that it relies on a saltwater rinse and gargle.

Worobey said he’s been collecting COVID-19 samples from patients in Tucson since March.

He wanted to find a way to test patients that didn’t include the nasopharyngeal swab method, in which a swab is inserted deep into the sinus cavity to collect respiratory mucosa cells.

Worobey told KTAR News 92.3 FM that he read on the pre-print server medRxiv about a group in British Columbia that was trying the mouthwash testing idea and figured he’d do the same in Tucson.

“They seemed to have pretty good success with it, where it was almost as sensitive as the nasopharyngeal swabs,” Worobey said. “And actually, it looked like it was quite a bit more sensitive than saliva tests, which have been developed.”

Worobey said he immediately got to work collecting samples from Tucsonans to compare how effective the mouthwash option was versus swabs and saliva tests.

His preliminary results found that the mouthwash tests were even more sensitive than other options, which he attributes to the fact that gargling reaches the cells that COVID-19 targets directly.

“It’s not totally clear but my guess is that compared to something like saliva is it’s a sort of value-added system where you probably get the same amount of saliva that a person would produce for just a direct saliva test,” he said.

“This approach gets saliva when you rinse the saline solution in your mouth. But when you gargle it also gets into the back part of your throat, called the pharynx. And so that’s where the nasopharyngeal swab is trying to get to, the nasal pharynx. And that’s where you have a lot of cells that can be infected by this virus.”

Worobey said the mouthwash test is only being used in his lab as part of a research study.

His department is providing samples to the lab on campus that handles clinical testing. Right now, the university’s lab is using traditional PCR tests on students, staff and faculty, according to Worobey.

Worobey said the department’s preliminary test results have been positive, with the next step being the implementation of the mouthwash testing method campus-wide.

“It’s just a question of how widely do we want to deploy this on campus,” Worobey said. “So I think that we’re in good shape in terms of the research sides of things has shown how well it works.

“We’re well into the validation on the clinical side and that will open the door to having this as a sort of official part of the armamentarium that we use.”

KTAR News 92.3 FM’s Ali Vetnar contributed to this report.

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