Trending Clinical Topic: Saliva

Ryan Syrek


April 09, 2021

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From new insights into its association with COVID-19 to a potential game-changing test to diagnose sports-related concussions, news about saliva made it this week's top trending clinical topic. A study published online in Nature Medicine found that SARS-CoV-2 infects mouth cells (see Infographic below). Researchers say this may help explain the taste and smell loss, dry mouth, and blistering that some patients experience. Coauthor Blake Warner, DDS, PhD, MPH, of the NIH's National Institute of Dental and Craniofacial Research, says, "This is really the first direct evidence that we have that SARS-CoV-2 can not only infect and replicate in cells of the mouth, but the fluid generated by the mouth is also infectious."

William Schaffner, MD, an infectious disease specialist at Vanderbilt University School of Medicine in Nashville, explained that the study makes it clear that "an unappreciated area of the body may play a role in COVID infections." Although the findings may have implications for diagnostic investigations, "For the average person, I don't think it means all that much except [that] you don't want to kiss someone who's got COVID," Schaffner said.

In terms of testing, previous studies had already found that testing saliva is nearly as accurate as deep nasal swabbing in diagnosing COVID-19. Considering that some have described the pain of a nasopharyngeal swab as feeling like their brain had been scraped, saliva sampling is a noninvasive alternative that appears to offer comparable results with less discomfort. Furthermore, rapid processing of saliva samples may be particularly beneficial in low- and middle-income countries, where swab availability may be limited. Specific guidance regarding laboratory diagnostics and testing for COVID-19 is under ongoing review and is frequently updated.

In non-COVID-related saliva news, researchers have identified a group of microRNA biomarkers that successfully diagnosed concussion in professional male rugby players. This could be a game changer, as it would represent a noninvasive test for mild traumatic brain injury. The biomarkers identified 96% of players with concussion in the Study of Concussion in Rugby Union through MicroRNAs (SCRUM) trial, a prospective, observational cohort study that enrolled 1028 male professional rugby athletes from the two top-tier leagues in England over two seasons. Although the data in the study only support the usefulness of saliva testing 36-48 hours postgame, the hope is that research may ultimately lead to the development of a rapid test that could be used on the sidelines.

Between new evidence on saliva's role in COVID and its use in various diagnostic tests, the fluid captured much attention this week, becoming the top trending clinical topic.

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