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Salivary Rt-Pcr Can Be A Valid Frontline Non Invasive Diagnostic Test For Detection Of Covid-19.

Rashmi, Vikas Deswal, Teena Wadhwa, Pooja Sharma, Manish K Singh, Smita Sarma, Sushila Kataria

Background: Cases of pneumonia of unknown aetiology were reported in Wuhan, China in December 2019. The disease was
identified to be caused by Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2) and was named Corona Virus Disease
2019 (COVID-19).
Methods: The samples (salivary and NPS) were randomly collected from 60 adults, who were clinically suspected of COVID-19
infection and reported to the hospital. Both samples were collected on day 0 and repeat sampling was done between day 7 ‒ day 14
for all the participants. All the samples were run for rRT-PCR. A Visual Analog Score form was used to evaluate patient comfort with the
procedure.
Results: Sixty participants were enrolled in this study which included 35 males and 25 females. The median age was 32 years (IQR:
25-51 years). A positive test by either sample route (saliva/NPS) tested by rRT-PCR was considered as true positive and considered as
reference standard. The 19 participants whose NPS tested negative for COVID-19, also tested negative with saliva (True negatives).
Out of 41 positive cases (True positives), 40(97.5%) were accurately diagnosed as SARS Co-V-2 positive with saliva and 37(90.2%) with
NPS. With saliva samples the sensitivity was 97.56%, specificity was 100%, positive predictive value was 100%, negative predictive value
was 95% and accuracy was 98.33%. Whereas with NPS the sensitivity was 90.24%, specificity was 100%, positive predictive value was
100%, negative predictive value was 82.61% and accuracy was 93.33%. The Ct values of both the sampling methods were comparable.
Saliva was also found to be more consistent. 70% of the participants found saliva as the preferred method of sampling.
Conclusion: Saliva is a viable, more sensitive, consistent and non-invasive method of sampling for COVID-19. It can be further
evaluated as a valid frontline non-invasive diagnostic test for detection of COVID-19.