Diagnostic accuracy of fresh drooled saliva for SARS-CoV-2 in travelers

Abstract

\n Background\n The standard for SARS-CoV-2 diagnosis is RT-PCR from nasopharyngeal or oropharyngeal swabs. Major airports require COVID-19 screening, and saliva has the potential as a substitute specimen for SARS-CoV-2 diagnosis. We investigated the utility of fresh drooled saliva against NPS for COVID-19 screening of travelers.\n \n Methods\n We recruited 81 travelers and 15 non-travelers (including ten controls) prospectively within a mean of 3·22 days of RT-PCR confirmed COVID-19. Each study participant provided 2\u202fmls of early morning fresh drooled whole saliva separately into a sterile plastic container and GeneFiX™ saliva collection kit. The saliva specimens were processed within 4\u202fh and tested for SARS-CoV-2 genes (E, RdRP, and N2) and the results compared to paired NPS RT-PCR for diagnostic accuracy.\n \n Results\n Majority of travellers were asymptomatic (75·0%) with a mean age of 34·26 years. 77 travelers were RT-PCR positive at the time of hospitalization whilst three travelers had positive contacts. In this group, the detection rate for SARS-CoV-2 with NPS, whole saliva, and GeneFiX™ were comparable (89·3%, 50/56; 87·8%, 43/49; 89·6%, 43/48). Both saliva collection methods were in good agreement (Kappa\u202f=\u202f0·69). There was no statistical difference between the detection rates of saliva and NPS (p\u202f>\u202f0·05). Detection was highest for the N2 gene whilst the E gene provided the highest viral load (mean\u202f=\u202f27·96 to 30·10, SD\u202f=\u202f3·14 to 3·85). Saliva specimens have high sensitivity (80·4%) and specificity (90·0%) with a high positive predictive value of 91·8% for SARS-CoV-2 diagnosis.\n \n Conclusion\n Saliva for SARS-CoV-2 screening is a simple accurate technique comparable with NPS RT-PCR.\n