Can You Swab Your Throat for COVID? Here's What Experts Say About Using At-Home Antigen Tests

Rapid tests that call for nasal swabbing really aren't designed to collect and analyze your saliva.

At-home COVID-19 antigen tests are in high demand, and for good reason. They're quick, convenient, and can help you contain the spread of the infection. That said, the FDA has acknowledged that certain rapid antigen tests may be less sensitive to the Omicron variant, prompting speculation that there's got to be a better way. On Twitter, some testers believe they've found it: enter, the pharyngeal (aka throat) swab, an at-home testing technique that's used alone or in conjunction with nasal swabbing.

Already part of the accepted practice in the UK and in Canada, throat swabbing videos from Public Health Ontario and UK Health Security Agency demonstrate how to collect an oral sample properly. They suggest using the provided test swab to sweep alongside the tonsils, avoiding the tongue and teeth, then proceeding to your regularly scheduled nasal swab, swirling around each nostril for roughly 15 seconds.

nose-throat-covid-test , A woman uses a home self testing kit for Covid-19
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Just like in US home-testing kits, the sample is then mixed with a solution known as a buffer, which contains salt and soap to break down cells. The sample/solution mixture is then applied to a test strip marked with stripes of antibodies that change color when COVID-19 antigens are present.

"As more countries continue the double-swab method, it may impact future FDA and CDC guidelines for those of us in the US. But it's important to reiterate that this method is currently not authorized by the FDA," says Jeffrey Dlott, MD, the medical director of consumer health at Quest Diagnostics, which conducts testing for COVID-19 and other infectious diseases.

Nevertheless, some medical experts in the US support throat-swabbing. On Twitter, Michael Mina, MD, chief science officer at eMed, a digital platform for supervised at-home testing, and former assistant professor of epidemiology at Harvard T. H. Chan School of Public Health, has been a stanch advocate for the testing technique. At deadline, he had not responded to Health's request for comment.

What's the science behind throat swabbing?

At face value, swabbing your throat to obtain a test sample sure makes sense: research published on the University of Hong Kong website suggests that Omicron starts in the lower respiratory system and multiplies there 70 times faster than the Delta variant and the original SARS-CoV-2 virus COVID-19 variants. This means that viral material might not get to your nose as quickly as symptoms come on, says molecular biologist Nathaniel Hafer, PhD, assistant professor at UMass Chan Medical School in Worcester.

Another theory that supports the throat swab: "The mutations in the COVID-19 Omicron variant may make it stick better in the throat or to saliva," says epidemiologist Clare Rock, MD, an infectious disease physician and associate professor of medicine at Johns Hopkins School of Medicine.

As such, "the combination of a throat and nasal swab may provide a more accurate result for at-home rapid antigen tests," acknowledges Dr. Dlott—especially if you're trying to capture as much virus as possible.

But more studies are needed. After all, in the absence of research, who knows whether at-home throat-swabbing could lead to false results, particularly when home users are operating without a standard set of directions.

See, in alternative tests that call for saliva collection, there tend to be very precise instructions: you either drool into a tube, swish out the secretions in your mouth before spitting into a tube, swab the inside of your cheek, or swab the back of the throat. "One might argue that you could get different results depending on which part of the mouth you sample," explains Hafer of UMass, who leads study logistics for school's National Institutes of Health-sponsored Rapid Acceleration of Diagnostics (RADx) initiative, which supports innovations in COVID-19 testing.

What's more, eating or drinking within 30 minutes of taking a throat swab can introduce acidity that interferes with the accuracy of the test, according to Dr. Rock, who likens at-home testing to following a recipe: "If you don't follow the instructions exactly, then you can not be sure you get the correct the result," she says. "It is important to use home COVID tests as directed."

Test makers echo this sentiment. Abbott, the manufacturer of BinaxNow, a popular at-home antigen test, told the New York Post that if users want to ensure accurate test results, it's important to follow the instruction for use. Abbott did not immediately respond to Health's request for comment.

The FDA also advises using the tests as directed. In a statement presented during an October 2021 weekly town hall for test developers and provided to Health, the agency advised that "COVID-19 tests should be used be used as authorized, including following their instructions for use regarding obtaining the sample for testing."

Is it possible to test negative with a nose swab and positive with a throat swab?

What's up with the anecdotal accounts of throat swabs being used safely and successfully to detect COVID-19 when nose swabs fall short? "It's difficult to answer this as we do not have the full scientific data available," Dr. Rock says. In one pre-print South African study, researchers found that PCR tests were more accurate in detecting the Omicron variant when using saliva samples versus nasal samples.

The thing is, the gold standard for medical data is peer review, and this study hasn't gone through that level of scrutiny. "We generally need more than one study to call something factual," Dr. Rock explains. What's more, the research in question relied on samples collected by medical professionals and involved PCR tests, highly-sensitive diagnostic tools that amplify viral genetic material to promote detection even after you cease to be contagious.

All of this is to say they work differently than at-home tests, which already get a bad rap for being less sensitive, but in truth are only designed to recognize antigens in highly contagious people. "PCR tests are ultra sensitive and pick up dead viral fragments even after you stop being contagious," says Jennifer Lighter, MD, NYU Langone Health epidemiologist and associate professor of pediatric infectious disease at NYU School of Medicine. "Antigen tests are only positive when you're contagious, but their sensitivity is actually excellent when you're symptomatic or have had close exposure."

Still, because antigen tests don't amplify the thing they are looking for, the sample you use for testing has to be a good one—and no one knows how human error might play into this equation when misusing at-home testing kits.

What might happen if I swab my throat, anyway?

Despite many signs that suggest you'd be smart to use your at-home test as directed, there will still be plenty of people who are frustrated by negative results after being exposed to COVID-19 exposure or experiencing symptoms and will want to try another approach before committing to an out-of-home PCR test. So what's the worst that could happen?

Performing a throat swab on oneself can be more complicated than a nasal swab since it's hard to get a good view of the back of your throat while getting all up in there. And if swabs are used incorrectly? They can cause harm to the patient, the FDA warned in its statement.

At the very least, you'd unpleasantly trigger a gag reflex—not ideal if you're already suffering from the nausea and vomiting, symptoms that can be associated with COVID-19.

"Testing both the throat and the nasal cavity with the same swab can be off-putting and, if done in the wrong order, may cause other infections," Dr. Dlott says. It could be one reason why the FDA is so intent on authorizing only nasal swabs for home-testers.

Of equal if not greater concern is the risk of reducing your test's accuracy: "There's a likelihood that it won't perform as indicated," Hafer warns of deviating from the directions.

A false negative can create a false sense of security that leads you to spread the virus to others unknowingly. But you could also get a false positive that contributes to unnecessary stress and isolation. "At the top of my social media feeds, people are putting tap water on tests and getting positive lines," Hafer says. "That doesn't mean there's COVID in the water. It means there are lots of ways to break the tests."

Once such way could involve the introduction of saliva from a throat swab. In FDA-approved at-home nose swab COVID-19 tests, the pH of the buffer is designed specifically for nasal swab specimens, according to Dr. Rock. Adding saliva to the mix could contaminate your sample and interfere with test results, she says.

Should you swab your throat on a rapid test?

The experts who spoke with Health agree that the answer is no—at least for now.

"The FDA has been recommending nasal sample tests because they are much more accurate than tests that use saliva or pharyngeal swab samples, and because the results from taking saliva samples and pharyngeal swab sample tests have not been very good so far," Hafer says. It's why he recommends sticking to the script the next time you take an at-home antigen test: "If it says, 'Take the swab and put it up one nostril, then the other,' then that's what people should do," he says.

Hafer is far from alone: "I follow the methods on the package instructions," says Dr. Rock, who prescribes the same course of action for non-medical professionals. The same for Dr. Dlott: "Until there are more studies and the FDA and CDC revise their guidelines, y advice would be to follow all the instructions that come with an at-home rapid antigen test, including how to swab."

Bottom line? "Right now, I would do what the instructions say," says Dr. Lighter. "There isn't enough evidence to make an alternative recommendation."

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