Saliva is superior over nasopharyngeal swab for detecting SARS-CoV2 in COVID-19 patients

Getachew Tesfaye Beyene,Anteneh Habte,Gebeyehu Assefa,Andargachew Mulu,Adane Mihret,Dessalegn Abeje Tefera,Melese Yeshambaw,Fekadu Alemu,Alemseged Abdissa,Tamirayehu Seyoum,Gadissa Bedada,Liya Wassie,Eyerusalem Solomon Kebede,Abebech Tesfaye,Birhanemeskel Tegene,Dawit Hailu Alemayehu

doi:10.1038/s41598-021-02097-2

Abstract

Scaling up of diagnostic capacity is needed to mitigate the global pandemic of SARS-CoV2. However, there are challenges including shortage of sample collection swabs and transport medium. Saliva has been recommended as a simple, low-cost, non-invasive option. However, data from different populations and settings are limited. Here, we showed that saliva could be a good alternative sample to diagnose COVID-19 patients. Pair of NPS-saliva samples was collected from 152 symptomatic; confirmed COVID-19 patients, and compared their positivity rate, viral load, and duration of viral shedding. From 152 patients, 80 (52.63%) tested positive and 72 (47.37%) were negative for SARSA-CoV2 in NPS sample. In saliva, 129 (92.14%) were tested positive and 11 (7.86%) were negative on the day of admission to hospital. The overall percent agreement of RT-PCR result of Saliva to NPS was 70% (196/280). A comparison of viral load from 72 NPS-saliva pair samples on day of admission shows saliva contains significantly higher viral load (P < 0.001). In conclusion, saliva has higher yield in detecting SARS-CoV2, and COVID-19 patients show higher viral load and prolonged period of viral shedding in saliva. Therefore, we recommend saliva as a better alternative sample to NPS to diagnose COVID-19 patients.

Highlights

Scaling up of diagnostic capacity is needed to mitigate the global pandemic of SARS-CoV2
All the samples were collected from patients who were detected positive for SARS-CoV2 RNA by reverse transcriptase polymerase chain reaction (RT-PCR) using nasopharyngeal swabs (NPSs) samples five to seven days earlier to their admission to the hospital
The gold standard test for the diagnosis of COVID-19 is the detection of SARS-CoV2 RNA by real-time RTPCR8,15 and the recommended sample is nasopharyngeal swab[9,15,16,17]

Summary

Introduction

Scaling up of diagnostic capacity is needed to mitigate the global pandemic of SARS-CoV2. Pair of NPS-saliva samples was collected from 152 symptomatic; confirmed COVID-19 patients, and compared their positivity rate, viral load, and duration of viral shedding. We recommend saliva as a better alternative sample to NPS to diagnose COVID-19 patients. In order to confirm SARS-CoV-2 infection, the world depends on the PCR based detection of viral RNA in various body fluids. Negative reports that have used multiple sample types, nasopharyngeal specimens were detected negative in some patients that were confirmed to have respiratory viral infections[11,12]. This study is aimed at investigating the diagnostic value of saliva samples for diagnosis of SARS-COV-2 infection in comparison to NPS

Methods

Results

Conclusion