LAUSR

Background:The gold standard for diagnosis of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) infection is reverse transcriptase real time polymerase chain reaction (RT-PCR) using respiratory samples. Collection of oro- nasopharyngeal swab (OP/NP) requires a trained health care worker (HCW) and appropriate biosafety conditions. There is need for a simpler strategy for sample collection without compromising the sensitivity. Saliva sample can be collected without any intervention of HCW. Therefore, the primary objective of the study was to evaluate efficacy of SARS -CoV-2 RT-PCR using self-collected saliva specimen. Methods:This pilot study was carried out at an ICMR approved molecular laboratory. The study population consisted of adults reporting to Flu OPD and hospitalized suspected COVID-19 cases. After obtaining consent, 3-5 ml of saliva was submitted in a universal sterile container by participants. Parallel (OP/NP) swab in viral transport medium (VTM) was also collected as per national guidelines. Both specimens were subjected to RNA extraction and SARS-CoV-2 RT PCR us- ing ICMR approved kit. Cycle threshold value of Envelope_Sarbeco gene (“E”), HKU Orf 1b gene (“HKU”) and Actin (Internal control) obtained for saliva and OP/NP swab were tabulated. Results:Saliva and OP/NP swab in parallel were collected from 85 individuals. The mean age of study population was 35.2 yr and 81% were male. The overall sensitivity and specificity of RT PCR on saliva sample was 95.6% and 92.5%. The concordance between ‘E” and “HKU” Ct value obtained by OP/NP and Saliva RT-PCR was 97.64% and 95.29%. The posi- tive and negative predictive value of the novel method was 93.5% and 94.9% respectively. Conclusions:Saliva collection requires lesser logistic requirement and saves VTM. Self-collected saliva is a reliable bio- logical sample and promising tool for SARS-CoV-2 testing in resource limited setting. Saliva RT-PCR could be cost- effective measure for laboratory capacity building.