Home saliva COVID tests are just as accurate as nasal swabs

As the pandemic rages on, research on different types of coronavirus tests continues in an effort to increase testing capacity and minimize contact with others.

Many Americans are familiar with the uncomfortable experience of having a 6-inch cotton swab poked deep in their nasal cavities, but there are also tests that can be completed at home that involve a simple spit in a tube — and they are just as accurate and reliable as their more painful counterpart, experts say.

Ever since the first emergency use authorization was issued for an at-home saliva-based COVID-19 test in May, the U.S. Food and Drug Administration has issued more for companies across the country.

Experts say they are easier to process in the lab, more comfortable for the patient and safer for health care professionals. The downside? Most at-home coronavirus saliva tests are costly, and in some cases, your insurance won’t cover the fees.

One test from Phosphorus Diagnostics that has received an FDA emergency use authorization — but has not been FDA cleared or approved — sells for about $150. This includes the test itself, telehealth fees and shipping costs, according to the company website.

Under the Coronavirus Aid, Relief, and Economic Security (CARES) Act, certain laboratory tests for the virus must be reimbursed by insurance, so the company says it can provide a receipt to file a claim.

All Albertsons and Safeway pharmacies are offering this saliva test in states such as Colorado, Alaska, Louisiana, Texas, Washington, Idaho, California and Arizona.

After filling out an online questionnaire that a physician reviews (hence the telehealth fee), a test is delivered to you and the spitting commences. The test must be sent to a designated lab that will return your results in about one to three days.

Some saliva tests don’t have to be done at home. The University of Florida, among other universities, is offering them to staff and students to speed up testing. But nasal swabs will not be fully replaced.

“Nasal swabs are still going to have a role,” Dr. Michael Lauzardo, deputy director of the UF Emerging Pathogens Institute, said in a university news release. “It will serve as a back-up when someone can’t produce enough saliva. And a nasal swab is required to do flu testing and coronavirus testing simultaneously. Saliva can’t do both. And that will be important if we have a significant amount of flu this winter.”

How accurate are saliva-based coronavirus tests?

Phosphorus Diagnostics says its test is 98% accurate, which aligns with what most other companies behind saliva tests report.

Experts call its accuracy “comparable” to the traditional COVID-19 nasal swabs, according to the University of Texas MD Anderson Cancer Center.

Research on a saliva test from the University of Chicago showed that when compared to nasal swab tests, the results matched up perfectly.

The researchers behind the test believe it could eliminate inconclusive results for patients who test negative for the virus, but still show symptoms, and for those who are asymptomatic.

“It’s possible that people who have the virus but don’t show symptoms have a smaller amount of virus that wouldn’t show up on (traditional) tests,” Dr. Jeremy Segal, an associate professor and pathologist at UChicago, said in a statement. “If they’re still able to spread the virus, being able to detect those people would be very important.”

Another coronavirus saliva test from Yale University only missed about 5% of positive cases, or 2 out of 37, and had no false positives when compared to nasal swab results. A separate one from Rutgers University also had no false positives or negatives — “that’s very promising,” the MD Anderson Cancer Center article said.

In its own study, the University of Utah Health found that self-collected saliva tests and nasal swabs collected by health care providers were “equally as effective” at detecting the coronavirus.

But when people swabbed their own noses without the help from medical professionals, nearly 15% of infections were missed, suggesting self-collected saliva is more accurate — and safer — than self-collected nasal swabs.

Besides the cost, at-home saliva tests have other disadvantages.

“There could be issues like do you have enough saliva to be able to spit enough into the tube?” Dr. Ken Stedman, a biology professor at Portland State University, told KATU2.

There’s also the issue of shipment delays.

“That’s one of the big concerns that we have with at-home testing in general is making sure that it gets to where it needs to be tested soon enough,” Stedman told the outlet. “Up to about 72 hours, it seems to be OK; beyond that, it starts to be a little problematic. Also, there are changes in temperature — did something sit on a dock somewhere for a little bit too long? Can you trust the result that you get?”

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Katie Camero is a McClatchy National Real-Time reporter based in Miami focusing on science. She’s an alumna of Boston University and has reported for the Wall Street Journal, Science, and The Boston Globe.

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