Saliva Tests Are as Accurate and Effective as Nasopharyngeal Tests in Precisely Diagnosing COVID-19, Finds Study

By HospiMedica International staff writers
Posted on 17 Feb 2021

A new study has shown that the less-invasive saliva test for COVID-19 gives just as accurate results as those of the nasopharyngeal specimen.

A research team at the Department of Laboratory Medicine at Kangwon National University School of Medicine (Seoul, Korea) carried out the PCR test for COVID-19 on 90 hospitalized individuals with suspected COVID-19, both with saliva and nasopharyngeal methods. In order to collect sufficient specimen, samples were collected from study participants, who were required to refrain from any activities including eating, drinking, and smoking, for 30 minutes after they got up in the morning.

Image: Allplex SARS-CoV-2 Assay (Photo courtesy of Seegene, Inc.)

For the study, the research team had used Seegene, Inc.’s (Seoul, Korea) COVID-19 tests, the Allplex SARS-CoV-2 Assay and Allplex SARS-CoV-2/FluA/FluB/RSV Assay. While the Allplex SARS-CoV-2 Assay targets four different genes of COVID-19, the Allplex SARS-CoV-2/FluA/FluB/RSV Assay is known to detect and differentiate eight target genes, including COVID-19, influenza and RSV common cold.

As a result, both the Allplex SARS-CoV-2 Assay and Allplex SARS-CoV-2/FluA/FluB/RSV Assay proved the saliva and nasopharyngeal test's percentage agreement for detecting COVID-19 was over 98.8%. That means COVID-19 diagnostic tests give equally accurate and effective test results for COVID-19 when testing saliva and nasopharyngeal specimen.

The research team also conducted a separate study on extraction-free application, one without the nucleic acid extraction step, and found the percentage agreement between Seegene's extraction-free saliva test and extraction-free nasopharyngeal swab test to be over 96%. In other words, the extraction-free method using the saliva sampling would be just as applicable for the PCR test in detecting SARS-CoV-2.

"The demand for saliva-based COVID-19 tests is on the rise, as the world still battles with short supply of specimen collecting swab for nasopharyngeal tests," said Professor Suh, the lead researcher of the study, adding that the study has "clearly proven that saliva tests are just as accurate and effective as nasopharyngeal tests in precisely diagnosing COVID-19."

Related Links:
Kangwon National University School of Medicine
Seegene, Inc.