Experimental Saliva Test Nearly Matches PCR for Accuracy

By Reuters Staff

December 09, 2021

(Reuters) - An experimental saliva test can diagnose SARS-CoV-2 infection in minutes, nearly as accurately as gold-standard PCR tests, researchers believe.

Typical saliva tests are unreliable unless done immediately after an overnight fast, because the concentration of virus particles in saliva drops steeply after eating or drinking.

Like other rapid antigen tests, this one, called PASPORT, binds the virus to nanoparticles. But PASPORT adds a second type of nanoparticle that binds to the first set, yielding a stronger signal and making the test more sensitive at finding the virus at any time of day, the researchers reported on in Microchimica Acta.

When tested on non-fasting samples from 139 volunteers - 35 with known COVID-19 infections and 19 with other respiratory infections - and compared to PCR tests of swab samples from the back of the nose and throat, PASPORT was 97% accurate at identifying SARS-CoV-2 and 91% accurate at ruling it out.

"Although PCR has been the gold standard, it requires trained personnel and laboratory infrastructure," study leader Dr. Danny Jian Hang Tng of Singapore General Hospital and Duke-NUS Medical School, said in a statement. A reliable, painless, affordable and convenient saliva test "would encourage more to be tested, and more frequent testing."

SOURCE: https://bit.ly/3Dzc7uF Microchimica Acta, online December 6, 2021.