Saliva tests for COVID-19 could replace painful nasal swabs, U. of C. researchers say

Researchers at the University of Chicago are exploring digital saliva testing for COVID-19, which could serve as a welcome alternative to the unpleasant deep nasal swabs that are currently used to get a thorough sample.

Early results show the new method is at least as accurate as the existing testing option, the researchers say. What’s more, scientists now believe saliva testing can prevent inconclusive results for those who test negative despite displaying symptoms and help ensure that patients don’t hold trace amounts of the virus before being discharged from hospitals.

U. of C. Professor Nishant Agrawal, a surgeon-scientist who is working on the study, said that the method “could provide clinicians with a quantitative measure of how much virus is present, beyond a simple yes or no.”

The new test relies on a droplet-digital polymerase chain reaction system that researchers believe could more accurately detect asymptomatic cases and positively identify cases with smaller amounts of the virus in a sample.

The research, which started in the spring, has largely been based around the University of Chicago Medical Center’s curbside testing site in Hyde Park. Because the system hasn’t been automated and it’s newer than the quantitative polymerase chain reaction technique that’s currently used, the various steps must be done by hand.

After hospital employees take a testing sample for a nasal swab, volunteers submit to a second swab and also give a saliva sample by spitting into a tube. The hospital tests the initial sample, and the research team runs the additional swab and the saliva sample using the new system, allowing the researchers to directly compare the methods.

So far, the results have “matched up exactly with the hospital’s results,” according to a news release.

“The beauty of it is that it’s less invasive, and you could allow people to collect their own samples,” said Evgeny Izumchenko, a researcher who serves as an assistant professor at the university. “[E]veryone knows how to spit.”

The research team is now exploring automated ways to run the tests, which will offer faster results and allow more to be conducted at once in the case of a resurgence of COVID-19 in the coming months.

Despite the encouraging findings, some questions remain.

Researchers have been surprised by how much the amount of virus has varied in those who have tested positive at the curbside location, which could present serious diagnostic challenges. And there’s also been early evidence that saliva tests could come back positive for a longer period than nasal swabs.