Scientists have demonstrated a quick and effective mass testing approach using saliva samples to detect individuals who have been infected with COVID-19 but are still not showing symptoms.
They tested and compared the nasopharyngeal swabs and saliva samples of almost 2,000 people in Japan who did not have COVID-19 symptoms. Two different virus amplification tests were performed on most of the samples: the PCR test, which is now well-known and widely available around the world, and the less commonly used but faster and more portable RT-LAMP test.
The number of positive and negative results in all samples was very similar, with the nasopharyngeal swabs and saliva samples able to detect those with the infection in 77–93 percent and 83–97 percent of subjects, respectively. Both two tests were also able to identify those without the infection in greater than 99.9 percent of subjects. The virus loads detected in nasopharyngeal swab and saliva were equivalent and highly correlated.
While finding both nasopharyngeal and saliva samples have high sensitivity and specificity to the SARS-CoV-2, the researchers says saliva testing has significant logistic advantages over the commonly used nasopharyngeal swab testing because it is painless for examinees, and more importantly, it eliminates the close contact with the examiners, reducing the risk of viral exposure.