Detection of SARS-CoV2 antigen in human saliva may be a reliable tool for large scale screening

Kannian, P.; Lavanya, C.; Ravichandran, K.; Jayaraman, B. G.; Mahanathi, P.; Ashwini, V.; Kumarasamy, N.; Rajan, G.; Ranganathan, K.; Challacombe, S. J.; Webster-Cyriaque, J.; Johnson, N. W.

Introduction: SARS-CoV2, the aetiological agent of the current COVID-19 pandemic, has been detected in saliva and recently implicated in several oral diseases. Collection of nasopharyngeal swabs (NPS) and detection by reverse transcriptase-polymerase chain reaction (RT-PCR) requires medical / technical expertise. A reliable and easy to handle point-of-care (POC) test is highly desirable, especially to curb transmission. Therefore, in this study, we evaluated a commercially available POC rapid antigen test (RAT) for the detection of SARS-CoV2 antigens in the saliva of RT-PCR confirmed positive and negative patients. Methods: Thirty saliva samples of 10 saliva RT-PCR negative and 20 saliva RT-PCR positive patients were tested by RAT. Results: RAT was negative in 10/10 (100%) RT-PCR-negative samples; positive in 9/20 (45%) RT-PCR-positive samples; concordance was 63% (p=0.001). Patients with positive RAT had higher virus copies in their NPS samples compared to the RAT-negative patients. This difference was also statistically significant (p=0.01). Conclusion: Thus, the POC RAT may be used to detect SARS-CoV2 as a reliable tool for self-testing, large-scale population screening and emergency medical/dental screening. Patients negative by RAT should be confirmed by RT-PCR.