coronavirus testing

How a Saliva-Based Test Could Transform Coronavirus Diagnoses

A health-care worker conducting a swab test, which may soon be swapped out for less-intrusive saliva tests. Photo: Getty Images

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“It’s awful, I’m sorry,” one health-care worker told a 17-year-old Utahn in March while conducting a coronavirus test in which a swab is placed deep into the nostril cavity. “I wish there was a better way to do it.” In addition to being uncomfortable, the nasopharyngeal swabs that have so far been necessary to conduct coronavirus tests often cause patients to cough or sneeze after the swab is removed, which makes full-body personal protective equipment necessary for those performing the test. But a new form of testing, in which patients spit their saliva into a cup, close the lid, and hand it to a health-care worker, could be an important tool in expanding COVID-19 testing — a necessity for safely reopening the country. Below is everything we know about the promising saliva tests, which may soon prove to be that better way.

How do saliva tests work?

Unlike the intense, one-on-one experience of the nasopharyngeal swab, a saliva test can be done on your own, reducing the risk of exposing others. A patient spits in a sealable cup — where it is immersed in a preservative — and hands it over to a lab technician, who determines if COVID-19 genetic material is in the sample. Results are available within 72 hours.

Are there any saliva tests currently in use?

In mid-April, after the Food and Drug Administration granted an emergency-use authorization to a lab from Rutgers University, the tests have been offered at a walk-up site in New Brunswick, New Jersey, drive-throughs in Somerset and Edison, in 30 long-term care facilities like nursing homes, and in some state prisons. The Rutgers lab has already processed almost 90,000 tests, and the lab’s head, Andrew Brooks, told the New York Times that it expects to be able to conduct as many as 30,000 per day.

The tests could soon be available in other states: Oklahoma is working with Rutgers to build its own version, and the lab has been in talks with the White House coronavirus task force and the states of Indiana, Illinois, and California for potential opportunities to expand. Currently, there are no at-home saliva tests, though Dr. Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security, told the Times that would be the likely next step for the technology: “If we can do nasal swabs unsupervised, there’s no reason why we can’t do these tests unsupervised as well.”

How can they help expand testing across the country?

While the painlessness of the procedure could make it more likely for people to seek treatment, saliva tests have also proven to be more reliable in lab studies: Swabs are more likely to produce false negatives and saliva tests appear to be more sensitive to genetic material in the sample. According to one Yale study, saliva tests were more accurate in testing mild cases. “The nasopharyngeal swab is subject to so much more variability in how well it’s obtained,” Anne Wyllie, the Yale team’s leader, told the New York Times. Part of that variability involves how well the health-care worker administers the swab, which can change based on the comfort levels of the patient getting a long Q-tip-like object stuck in their nose, and the resoluteness of the provider executing the uncomfortable routine.

“If people are going back to work, and they’re going to be tested presumably on a regular basis, we really do need to less invasive sampling methods than the swabs,” Angela Rasmussen, a virologist at Columbia University, told the New York Times. “To have to do nasopharyngeal swabs twice a week? No, thanks.”

Are there any potential problems with the tests?

While Rutgers researcher Andrew Brooks told the Washington Post that he anticipates saliva testing will allow three times as many people to get tested per day while reducing the need for PPE among those testing by 90 percent, the Times notes that the thermal cyclers used for saliva tests — machines which amplify viral genetic material for testing — require labs to use chemical supplies made by the manufacturer. According to Dr. Rasmussen, “that could potentially be a supply issue” as states hope to implement the testing. And though Brooks expects that they will be able to shorten the wait for results, the 72-hour delay is a far cry from some swab tests which can identify a coronavirus-positive patient in minutes.

A Saliva-Based Test Could Transform Coronavirus Diagnoses