A new study has found that a coronavirus saliva test protocol developed by Yale University researchers seemed to perform as good as nasal swabs, which may encourage more frequent use of self-collected samples.
Dr. Anne Wyllie of the Yale School of Public Health and her team conducted testing on 70 hospitalized patients who were already tested positive for COVID-19 through nasal swab specimens.
After 1 to 5 days of diagnosis, more than 80% of the saliva samples were positive compared to 71% of the nasopharyngeal swab specimens.
Dr. Wyllie and coauthors published their findings in the New England Journal of Medicine.
Dr. Wyllie told Medscape Medical News that 76% of the saliva test was positive at days 6 to 10 after diagnosis compared to 65% of the nasal swab specimens.
The researchers also published screening results for 495 healthcare workers who were asymptomatic for COVID-19. They detected the virus in saliva specimens obtained from 13 people who had no symptoms at or before the time of sample collection.
Of those 13, nine had collected matched nasal swab specimens by themselves on the same day and seven of these specimens tested negative. “The 13 positive diagnoses were later confirmed with additional nasopharyngeal samples.”
Jason Farley of Johns Hopkins Schools of Nursing and Medicine told Medscape Medical News that these findings represent “an important advance in testing” for COVID-19.
Farley, who was not involved in the Yale team’s work, has worked on efforts at Hopkins to test individuals using saliva samples to detect COVID-19 infection.
He said, “The pragmatic approach used by the Yale team avoids the kind of issues with shortages of medical supplies that have hampered US testing. This moves us forward, especially with supply-chain issues.”
Last month, Dr. Wyllie and Dr. Nathan Grubaugh of the Yale School of Public Health secured an Emergency Use Authorization (EUA) from the Food and Drug Administration (FDA) for a saliva-related test protocol, known as SalivaDirect.
SalivaDirect is not a kit but a protocol that is intended to help other institutions to do “inexpensive saliva-based” testing.
Farley said, “I love the fact that they are sharing their protocols in an open-source way so that people can replicate the protocol. The Yale team really needs to be commended for that level of scientific integrity.”
Dr. Martin Burke of the University of Illinois, Urbana-Champaign, said, “I’m hopeful it is going to help overcome that inertia and help us get to a place where we could test much more [quickly] and frequently.”
“Saliva is the medium that matters,” he added. “This is how we transmit SARS-Cov2 to one another primarily. So why not test the thing that is most important for that transmission?”
Dr. Wyllie said their study shows the saliva test to be at least as good as, and possibly better than, the nasal swab test. She said greater availability and ease of coronavirus tests is critical to prevent the spread of the virus. “People need to stop thinking about just diagnostic testing,” Dr. Wyllie added. “We need to have screening testing going forward. These screening tests don’t necessarily have to be of the same standards as diagnostic tests.”
