Doctors Question New Saliva Test for COVID-19

The Food and Drug Administration (FDA) recently granted emergency use authorization for a new rapid saliva test that could help diagnose COVID-19 in three hours. The test, created by researchers at Yale University, may help alleviate the strain on diagnostic resources in labs across the country. But doctors are concerned about its accuracy.

SalivaDirect, cleared by the FDA on August 15, is simpler, less expensive, and less invasive than using a nasopharyngeal swab to test for SARS-CoV-2, the virus that causes COVID-19. The test isn’t perfect, and there is some room for a false negative result. A pre-print publication in medRxiv found that the SalivaDirect test had comparable results to a nasopharyngeal swab 94% of the time.

"A few months ago, I would have said I would not be interested in this," Rajeev Fernando, MD, an infectious disease expert in Southampton, New York, tells Verywell. However, Fernando adds, “we’re still short on testing. We don’t have enough machines, and polymerase chain reaction (PCR) testing—the diagnostic test of choice—is very labor-intensive.”

A Faster Way to Test More People

Since some patients currently have to wait up to two weeks to get results of COVID-19, Fernando says this kind of rapid test may help reduce the backlog.

“I would use this more to test large populations or people who are not really sick,” he says. “It’s a good way to screen people who are low-risk. But if a patient has symptoms and gets a negative saliva test, I would follow that up with a PCR test.”

Richard Watkins, MD, an infectious disease physician in Akron, Ohio, is hopeful that this particular test may help free up testing capabilities for PCR tests and reduce supply issues with regard to testing swabs.

"On the one hand, I am happy that testing can be expanded, and this is a way to potentially get a lot more people tested," Watkins, who is also an associate professor of internal medicine at the Northeast Ohio Medical University, tells Verywell. “But on the other, I am concerned about the risk for false negative test results.”

How Does This Saliva Test Work?

With the SalivaDirect test, patients collect a sample of their own saliva under the guidance of a healthcare professional. Since the sample is collected by the patient, it could lower the risk of exposing healthcare workers to COVID-19, the FDA says.

SalivaDirect also doesn’t require any special type of swab or collection device. Instead, a saliva sample can be collected in any sterile container.

This isn’t the first saliva test to get FDA emergency use authorization; it’s actually the fifth, the agency said in a press release announcing SalivaDirect’s approval.

However, this test is unique in that medical personnel don’t need to separate a patient’s genetic material, called nucleic acid, from the sample.

“This is significant because the extraction kits used for this step in other tests have been prone to shortages in the past,” the FDA says. “Being able to perform a test without these kits enhances the capacity for increased testing, while reducing the strain on available resources.”

Currently, the NBA is using SalivaDirect to test asymptomatic players and staff, according to a press release from Yale. Now, with the FDA’s emergency use authorization, the testing is immediately available to other organizations and labs.

Ultimately, experts say this new test is a good supplemental diagnostic tool.

“I certainly think there is an indication for this test in this climate,” Fernando says. “But I wouldn’t only rely solely on it.”

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