The pros and cons of COVID-19 saliva tests, as Alberta explores testing method

Click to play video: 'As Alberta explores possible saliva tests, the benefits and disadvantages of this testing method'
As Alberta explores possible saliva tests, the benefits and disadvantages of this testing method
WATCH ABOVE: British Columbia is piloting saliva COVID-19 tests, in which students swish, gargle and spit a small amount of saline into a collection tube. Alberta is exploring the idea as well, so what are the advantages and downsides, and how does it compare to the traditional tests? Julia Wong takes a look. – Sep 25, 2020

As demand remains high on supply chains connected to COVID-19 testing, some provinces are moving towards a new type of test: a gargle test involving saliva, which is an option the province of Alberta is exploring.

READ MORE: So long swabs: B.C. unveils new mouth-rinse COVID-19 test for kids

In British Columbia, children from kindergarten to Grade 12 swish, gargle and spit a small amount of saline into a collection tube.

“Globally it’s been a challenge getting a lot of these [nasopharyngeal] swabs but also collecting those samples. That’s particularly challenging in children, to have trained healthcare providers available that can safely collect these from children,” said Dr. David Goldfarb, a medical microbiologist at B.C. Children’s and Women’s Hospital.

“We were looking at swab-free ways of collecting samples that could be self-collected.”

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READ MORE: Saliva tests could make spotting coronavirus easier: expert

A shift to a different testing method could decrease reliance on certain testing products, thereby reducing bottlenecks and limitations on the supply chain.

Dr. Lynora Saxinger, an infection disease specialist at the University of Alberta, said the nasopharyngeal swab can be uncomfortable for people.

The throat swab can often make the recipient gag.

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Edmonton International Airport to pilot rapid-response COVID-19 saliva test

A saliva test could remove obstacles to testing for children, seniors and others who find the deep nasal swab uncomfortable. There may also be advantages to a collection that is more self-sufficient.

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“You need a trained healthcare worker to do a throat and nasal swab; that means you’ve got a scarcity of people who can actually do it so you have longer lines,” said Colin Furness, an infection control epidemiologist at the University of Toronto.

“You don’t need a trained healthcare worker to collect a saliva sample so that becomes a lot easier, no question.”

Dr. Jason Kindrachuk, an assistant professor and Canada Research Chair in Emerging Viruses at the University of Manitoba, said the sensitivity of a saliva test is comparable to other tests already on the market, though he admits there are some caveats when it comes to the window to get tested.

“If you happen to test somebody at the very early stages of infection, perhaps a saliva test might miss that or see that as a negative.

“But the swab test, because it is a little bit more sensitive, might be able to pick that up at an earlier frame in time,” he said.

“At that point where people are symptomatic, the virus is likely at or very close to its peak, which means that either of those tests should likely pick that up with a high degree of sensitivity.”

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Furness, however, said the trade-off could be worth it.

“If you’re able to test way more people that makes up for the fact it’s not nearly as sensitive because you will still pick up cases you might not otherwise have picked up,” he said.

Saxinger said it is important to evaluate and validate any test before it is used in Alberta.

She said there may be different processes for handling samples from a saliva test and there could be added risk for lab operators. It is unclear, at this point, how or whether a test involving saliva would impact processing times in the lab.

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“At the end of the day, you still actually have to run the sample. You have to process the sample to extract the viral RNA and you have to do a PCR test for it.

“At the end of the day, that still has to be done for all the samples,” she said.

Alberta’s chief medical officer of health said Alberta Health is working with the lab on options such as the mouth rinse and self-saliva sample.

“There are different elements that need to be put in place before that can be used broadly,” Dr. Deena Hinshaw said on Sept. 18.

“We need to make sure that that methodology will work with the way that our lab runs tests. We need to make sure that we have adequate collection containers, all of those different pieces because, of course, all of the hardware and infrastructure that goes along with a new sample methodology needs to be validated to make sure that it does provide an accurate result and that work is underway in Alberta but I don’t have a timeline as to when it might be able to be moved forward.”

with files from Caley Ramsay


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