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Some at-home saliva tests need to be sent to a lab. Others don’t. D3sign/Getty Images
  • Researchers say new saliva tests are nearly as accurate as throat and nasal swabs to detect COVID-19.
  • They note that the tests are easier and less invasive than other exams, factors that could help increase the number of COVID-19 tests.
  • Some at-home tests require a prescription, and some need to be sent to labs while others don’t.

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You now have a more comfortable, easier-to-perform option for COVID-19 testing besides the “stick in the nose” and throat swab methods.

Saliva-based testing has shown accuracy in detecting positive coronavirus infection 83 percent of the time, while nose-throat swab tests have shown 85 percent accuracy, according to a review of data from 16 studies including 5,900 participants published in JAMA Internal Medicine.

The study authors also report that saliva-based testing has shown 99 percent accuracy at identifying negative cases for COVID-19, with a far less invasive and discomforting process.

Furthermore, the researchers suggest that the ease of use and good diagnostic performance of the saliva-based test may make it an attractive alternative that could bolster test rates.

Dr. Seema Kumar, a medical director at Mytonomy, said at-home testing decreases the risk of COVID-19 exposure, increases access to testing, and reduces the burden on laboratories.

She said these are all critical benefits during the ongoing and ever-evolving pandemic.

“These tests are best used for those with mild symptoms or a known or suspected exposure to someone with a COVID-19 infection,” Kumar told Healthline.

“Saliva testing is very sensitive. It can detect the virus as well as one copy per microliter of saliva,” added Dr. Spencer Kroll, FNLA, an internal medicine specialist in New Jersey.

“It is reassuring that many saliva test kits show high concordance with nasal swab polymerase chain reaction (PCR) testing for SARS-CoV-2 detection,” he told Healthline.

However, Kroll said that the approximate mismatch of saliva testing versus nose-and-throat swab testing leaves room for missed cases that could have otherwise been detected with a nasal swab PCR test.

“Therefore, negative saliva results do not absolutely preclude SARS-CoV-2 infection and should not be used as the sole basis for patient management decisions,” he said.

“Negative results must be combined with clinical judgment, patient history, and epidemiological data,” Kroll said.

Kumar agrees.

“Test results are interpreted in context of symptoms, possible or known exposures, and prevalence of disease within the community,” she said.

Importantly, “sometimes a repeat test is needed,” Kumar said.

“The home testing offers convenience, but it is always best to review your results and questions with your healthcare provider,” Kumar said.

The Food and Drug Administration (FDA) says that a negative test means COVID-19 was not found in your test specimen.

While this typically means you’re free of the novel coronavirus, it’s important to remember that no currently available test is 100 percent accurate.

“It is possible for a test to give a negative result in some people who have COVID-19 (that is, a false negative),” states the Centers for Disease Control and Prevention (CDC). “Discuss your symptoms and test results with your healthcare provider to determine if you need follow-up testing.”

Kumar said false negatives can be a result of factors such as test accuracy but also timing of the test and sample collection.

Kroll advises testing to be performed after a requisite amount of days, “or the test will provide a false negative result and this same concept holds true with healthcare facility testing for coronavirus,” he said.

“Patients should not test before 5 to 7 days after exposure — even with symptoms — and they should consider themselves potentially infectious until that time and until proven to be COVID-19 negative by a home test,” Kroll said.

“It is best to err on the side of caution to reduce the risk of spread to others,” Kumar added.

“If an individual has symptoms suggestive of COVID-19 or a known exposure to COVID-19, it is important to discuss with your healthcare provider to determine if you need follow-up testing,” Kroll said.

Kroll said many things can interfere with testing results.

He said that multiple interfering agents have been tested and don’t appear to impede the accuracy of saliva testing.

These include decongestant nasal sprays, steroid nasal sprays, sore throat lozenges, blood, toothpaste, and mouthwash.

But possible false results could come from contamination with food and other substances, Kroll said.

“Smoking tends to dry the mouth and might reduce the ability to produce an adequate specimen,” he said. “It is also theoretically possible that alcohol could denature the viral RNA so that it cannot be amplified and detected in the test.”

“Appropriate precautions for potentially interfering substances and proper self-collection of samples is necessary,” Kroll noted.

The good news, Kumar said, is the at-home tests come with easy-to-follow instructions. This can help reduce margins of error.

In November, the FDA granted emergency use authorization for people to collect specimens (nasal swab or saliva) in their home or in a private location.

This means you can conduct your own COVID-19 test through an at-home test collection kit.

Some tests are sent to a testing facility while others aren’t sent to a laboratory.

Kumar said results can be obtained as quickly as 30 minutes.

The quickest way to access a test is to contact your healthcare provider to see if at-home testing is the right option for you.

This doesn’t mean you necessarily have to visit a clinic, though. Due to the ongoing pandemic, many appointments, including those requesting prescriptions for at-home testing, have gone online. Simply ask for a virtual appointment.

Most at-home test collection kits are by prescription, but some are available over-the-counter.

Some tests may also require a health assessment or a laboratory order.

Due to the differences between tests and test providers, some are available free of cost where others are discounted through certain insurance companies.

More information on specific tests available free of cost and for purchase can be found through the FDA or in this Healthline article.