Performance of SARS-CoV-2 Real-time RT-PCR Tests on Oral Rinses and Saliva Samples

Babady, N. Esther; McMillen, Tracy; Jani, Krupa; Viale, Agnes; Robilotti, Elizabeth V.; Aslam, Anoshe; Diver, Maureen; Sokoli, Desiree; Mason, Greg; Shah, Monika K.; Korenstein, Deborah; Kamboj, Mini

Access to rapid and accurate detection of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) RNA is essential for controlling the current global pandemic of Coronavirus Disease 2019 (COVID-19). In this study, the use of oral rinses and posterior oropharyngeal saliva as an alternative to swab collection methods from symptomatic and asymptomatic healthcare workers for the detection of SARS-CoV-2 RNA by RT-PCR was evaluated. For saliva samples, the overall agreement with oropharyngeal swabs (OPS) was 93% (Ƙ=0.84) with a sensitivity of 96.7% (95%CI:83.3-99.8%). The agreement between saliva and nasopharyngeal swabs was 97.7% (Ƙ=0.93) with a sensitivity of 94.1% (95% CI:73.0-99.7%). Oral rinses were compared with NPS only, with an overall agreement of 85.7% (Ƙ=0.65), and a sensitivity of 63% (95% CI:46.6-77.8%). The agreement between a laboratory-developed test based on the CDC RT-PCR and two commercial assays, the Xpert Xpress SARS-CoV-2 and the Cobas SARS-CoV-2 was also evaluated. The overall agreement was higher than 90%. Finally, SARS-CoV-2 RNA in saliva samples was shown to be stable, with no changes in viral loads over 24 hours at both room temperature and 4ºC. While the dilution of SARS-CoV-2 in oral rinses precluded its acceptability as a sample type, posterior oropharyngeal saliva was an acceptable alternative sample type for SARS-CoV-2 RNA detection.