Saliva also has a trade-off. When the virus appears early in the saliva, the nose may be a better place to detect it during infection.
Researchers at the California Institute of Technology found that when the virus often grows in saliva for the first time, it eventually reaches a high level in the nose. Their results suggest that highly sensitive tests, such as PCR tests, may be able to detect saliva infections before nasal swabs, but less sensitive tests, such as antigen tests, may not.
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Some experts have noted that the data on saliva is still mixed.
“These are just a few of the studies I’ve found to be really interesting,” he said. Mary K. Infectious Disease Physician and Clinical Microbiologist at Rush University Medical Center in Hayden, Chicago.
But Dr. Hayden said she was cautiously interpreting the new studies because “over the years and years,” research has shown that nasopharyngeal samples are best for detecting respiratory viruses.
Some scientists also have practical concerns. The mouth is “slightly higher in an uncontrolled environment than in the nasal passages,” said biochemist Joseph Dirisi of the University of California, San Francisco, who is president of the Chen Zuckerberg BioHub and author of the cheek swab paper. . “Did you drink Coke before you took the test?” The pH will be different. And those things are important. “
Saliva can be “viscous and difficult to deal with,” especially when patients are sick and dehydrated. Mary-Louis Landry, director of the Clinical Virology Laboratory at Yale New Haven Hospital, said in an email.
Ultimately, different approaches may require different approaches. For those who have had symptoms for several days, a nasal swab may be a good choice, while saliva may be the most suitable for large-scale supervised screening of asymptomatic people, Drs. Suggested to Haynes. “We need to get the right test in the right places,” he said.