Salivary detection of COVID-19. Clinical performance of oral sponge sampling for SARS-CoV-2 testing

Abstract

Background The current diagnostic standard for coronavirus 2019 disease (COVID-19) is reverse transcriptase-polymerase chain reaction (RT-PCR) testing with naso-pharyngeal (NP) swabs. The invasiveness and need for trained personnel make the NP technique unsuited for repeated community-based mass screening. We developed a technique to collect saliva in a simple and easy way with the sponges that are usually used for tamponade of epistaxis. This study was carried out to validate the clinical performance of oral sponge (OS) sampling for SARS-CoV-2 testing. Methods Over a period of 22\u2005weeks, we collected prospectively 409 paired NP and OS samples from consecutive subjects presenting to a public community-based free screening center. Subjects were referred by their attending physician because of recent COVID-19 symptoms (n=147) or by the contact tracing staff of the French public health insurance since they were considered as close contacts of a laboratory-confirmed COVID-19 case (n=262). Results In symptomatic subjects, RT-PCR SARS-CoV-2 testing with OS showed a 96.5% (95%CI: 89.6–94.8) concordance with NP testing, and, a 93.2% (95%CI: 89.1–97.3)] sensitivity when using the IdyllaTM platform and a sensitivity of 76.3% [69.4–83.2] on the Synlab Barla laboratory platform. In close contacts the NP-OS concordance (93.8% [95%CI: 90.9–96.7]) and OS sensitivity (71.9% [95%CI: 66.5–77.3]) were slightly lower. Conclusion These results strongly suggest that OS testing is a straightforward, low-cost and high-throughput sampling method that can be used for frequent RT-PCR testing of COVID-19 patients and mass screening of populations.