Saliva test may prove easier — if it’s accurate
Stanford researchers are developing a test that can diagnose the coronavirus by analyzing saliva collected in a small cup, which — if proven reliable and accurate — could make testing more accessible, cheaper and less invasive.
The work comes as the Food and Drug Administration recently authorized the use of the first athome coronavirus saliva test, made by a lab at Rutgers University in New Jersey, which is working with companies to manufacture and distribute thousands of the tests to health care providers, nursing facilities and homes across the United States.
The current gold standard for coronavirus testing is done by collecting a nasopharyngeal specimen, which requires health care workers to stick a swab several inches into a patient’s nostrils and can be uncomfortable. It also requires
health care workers to wear headtotoe personal protective equipment, or PPE, because the swabbing can prompt a sick patient to sneeze or cough and expose the worker to the virus.
Stanford began working on its saliva test a few weeks ago, said Stanford’s Dr. Yvonne Maldonado, an epidemiologist and infectious disease specialist. Stanford can process the saliva tests using the same lab equipment it already uses to run the nasal samples. But to get the FDA to sign off on the saliva tests, researchers must show they can detect the coronavirus as well as the nasal test can.
To do so, Stanford is trying to test 20 COVID19 positive patients and 20 COVID19 negative patients using both types of tests to see if the results match up. That means some patients tested at Stanford drivethrough testing sites, clinics and hospitals will do both kinds of tests: receive a nasal swab and spit into a cup.
“We know (the saliva test) will work in the lab, but we don’t know how often it’ll identify a positive that the gold standard will identify,” Maldonado said. “That’s where we are now.”
Similar to tests that analyze nasal specimens, saliva tests detect the presence of the virus’ RNA.
There are limitations to saliva tests. The FDA notes that the collection of saliva specimens is limited to patients with symptoms, and that negative results should be confirmed by testing an alternative specimen. Saliva tests may not be able to detect the virus in asymptomatic people because there may not be enough virus present in the saliva specimen.
“Saliva clearly looks appealing, but there are limitations,” said Nam Tran, senior director of clinical pathology in charge of COVID19 testing at UC Davis Health. “We are currently not actively looking at a saliva test due to these concerns.”
Yet an April 24 study by the Yale School of Public Health, which has not been peer reviewed, found that saliva samples are a viable alternative to nasal swabs because they are less invasive, can be selfadministered and have comparable sensitivity to nasal swabs. The study looked at 44 hospital patients and 98 health care workers at Yale New Haven Hospital.
Maldonado said Stanford researchers hope to have results in the next few weeks. But it’s been a challenge to find 20 positive patients because there’s been a slowdown of new COVID19 infections in the Bay Area, she said.
If the Stanford test receives FDA authorization, it may eventually be sent to people’s homes so they can collect the sample themselves.
“Any tests we can build out that help make it easier to diagnose someone and keep them healthy and keep them isolating, and keep them from infecting other people would be useful,” Maldonado said. “A saliva test could be so much easier. People could just spit in a cup. You don’t need to be near a health care provider. It’s cheaper and easier. It doesn’t expose others to secretions.”
The only coronavirus saliva test to receive FDA emergency use authorization so far, on April 13, was developed by RUCDR Infinite Biologics, a Rutgers University lab. On Friday, the federal agency went a step further, granting authorization for the test to be used at home. Consumers can request the test, but it requires a doctor’s order. Patients spit into a small tube and then screw the cap on, which releases a preservation solution into the saliva.
Rutgers has partnered with Spectrum Solutions, a Utah company that manufactures the saliva collection kits. Another company, Tennesseebased Strategic Lab Partners, is working with Spectrum Solutions to distribute the tests.
Strategic Lab Partners has shipped 1.2 million saliva test kits, including to California hospital groups and employ
“There are mixed reports on whether saliva is a good sample type.”
Dr. Steve Miller, UCSF Clinical Microbiolog y Laboratory director
ers, said Will Lane, the company’s founder. Lane declined to say which California companies and health care providers purchased the tests, citing nondisclosure agreements. The Rutgers test is also being used in nursing homes, developmental centers and health care networks in New Jersey, New York and elsewhere, said Andrew Brooks, chief operating officer of RUCDR Infinite Biologics.
Several major health systems in the Bay Area, including Kaiser Permanente and UCSF, have not adopted the use of saliva tests, saying they are monitoring new tests as they come onto the market to make sure they are accurate.
Dr. Steve Miller, professor of laboratory medicine and director of the UCSF Clinical Microbiology Laboratory, said UCSF is not using saliva testing to diagnose the coronavirus and is looking into whether saliva and other types of specimen samples will produce reliable coronavirus test results.
“There are mixed reports on whether saliva is a good sample type, with some studies limited to earlymorning collections, which is not compatible with patient testing in a health care setting,” he said. “In our experience, saliva samples are often difficult to work with in the lab due to some samples being foamy and mucoid, and many of these do not provide valid results upon testing.”