Study Backs Use of Saliva COVID-19 Test

Sept. 4, 2020 — A COVID-19 saliva test developed by researchers at Yale University appeared to perform at least as well as nasal swabs in a study of hospital patients, a finding that may help encourage more frequent use of self-collected samples.

In a letter published Aug. 28 in TheNew England Journal of Medicine, Anne L. Wyllie, PhD, of the Yale School of Public Health, and her co-authors reported on testing done on 70 patients. These patients already had tested positive for COVID-19, which was confirmed with a positive nasal swab.

One to 5 days after diagnosis, 81% of the saliva samples were positive, as compared with 71% of the nasal swab tests, Wyllie and co-authors say.

The New England Journal of Medicine (NEJM) publication expands on work previously reported by Wyllie and colleagues in an April preprint article posted to the site medRxiv.

These findings represent “an important advance in testing” for COVID-19, says Jason Farley, PhD, of Johns Hopkins Schools of Nursing and Medicine in Baltimore. An infectious disease-trained nurse epidemiologist, Farley was not involved in the Yale team work, but he has worked on efforts at Hopkins to test people using saliva samples to track COVID-19 infection.

The approach used by the Yale team avoids the kind of issues with shortages of medical supplies that have hampered U.S. testing, Farley says. Their approach relies on supplies hospital labs are likely to have on hand. The letter in NEJM, for example, said sterile urine cups were used to gather samples.

“This moves us forward, especially with supply chain issues,” he says of the new research.

Wyllie and Nathan Grubaugh, PhD, of the Yale School of Public Health, last month secured an emergency use authorization from the FDA for a related test protocol, called SalivaDirect​. The FDA said this was the fifth test it had authorized that uses saliva as a sample for testing for COVID-19. ​

But Yale’s approach with SalivaDirect is different from that used with many diagnostics.

“A common question that we receive is, ‘What company is behind this assay?’ The answer is — well, there isn’t one. We designed and validated SalivaDirect using several common and available reagents. If one reagent is out of stock or is too pricey, there are alternative reagents to use,” says a paper on the CovidTrackerCT website, created by members of Grubaugh’s lab.