Validation of Saliva Biospecimen; an Alternative to Nasopharyngeal Swab detection of Sars- Cov 2using TR- PCR

Abstract

Extensive and widespread testing is necessary to control the rapid spread of SARS-CoV-2 pandemic which has been rampant since its origin in 2019. The current gold standard for COVID testing, nasopharyngeal sampling (NPS) method presents various obstacles for a successful mass testing like need of highly trained personnel, transport media, personal protective equipment (PPE). Hence, we have tried to establish saliva sample as an alternative to NPS. In this study, patients visiting the KM biotech lab for PCR test were asked to provide saliva samples in addition to NPS sample. The saliva sample is then heat killed and directly processed for PCR amplification. The corresponding data from NPS and saliva samples are compared to gauge efficiency of saliva against NPS. We observed that the saliva is effective as NPS with sensitivity (80%) and specificity (91%) [P<0.01]. We found that 60% (110/180) samples tested positive in either or both the NPS and saliva test, while 21(11%) samples tested positive in NPS only and 7(4%) samples tested positive in saliva only. In conclusion, saliva assay demonstrated significant results against the NPS samples. Saliva assay could prove effective in controlling COVID pandemic when compared to painful and resource intensive NPS sample. This study is relevant, especially in case of countries like Nepal, where we are completely dependent on international market for transport mediums, PPE, swabs etc. Saliva assay could reduce our dependence significantly as it has substantially less resource requirements. Keywords: SARS-CoV-2, COVID-19, Saliva assay, NPS, COVID testing, RT-PCR