Use of saliva as an alternative diagnostic method for diagnosis of COVID-19

Background: Mass population testing has been recommended to contain the spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. However, the use of nasopharyngeal swab specimens has caused many logistic challenges. This study investigated the sensitivity and specificity of saliva as a non-invasively-obtained specimen for molecular detection of SARS-CoV-2 RNA.

Methods: In total, 153 patients with confirmed coronavirus disease 2019 (COVID-19) who had been admitted to the regional referral hospital or who self-isolated at home were included in this study. Nasopharyngeal swab specimens and saliva samples were collected on the same day, and were tested for SARS-CoV-2 infection using reverse transcriptase polymerase chain reaction.

Results: The sensitivity and specificity of saliva samples were 81.5% and 76.4%, respectively, in cases that had been confirmed as COVID-19 using nasopharyngeal swab samples. Positive predictive values and negative predictive values were 92.3% and 54.1%, respectively. The highest detection rates were found among samples collected 4-7 days since symptom onset.

Conclusion: Saliva samples showed comparable performance to nasopharyngeal swab specimens for the diagnosis of COVID-19 in adults. The performance of saliva as a diagnostic specimen for COVID-19 testing is particularly significant during the first week of symptoms.