ABSTRACT
Introduction: SARS-CoV-2 viral infection and the consequent COVID-19 disease rolled over the globe sweeping human lives and national health systems. Early diagnosis plays an important role in stopping its further escalation. Saliva as a Diagnostic Tool: Reverse transcription polymerase chain reaction (RT-PCR) remains the gold standard in the diag- nosis of COVID-19 disease. Nasopharyngeal/oropharyngeal swabs are the recommended specimen types for identification of viral RNA. However, false negative results may occur due to inadequate or improper oropharyngeal sampling. Saliva, as a prom- ising alternative, circumvents the limitations associated with the use of nasopharyngeal/oropharyngeal swabs and lessens the exposure risk of health care professionals. Salivaomics or salivary diagnostics includes the study of salivary proteins, salivary RNAs, salivary metabolites, salivary microR- NAs and salivary microbiota. Saliva sample collection is easy, non-invasive and more acceptable for repeat testing and can be performed by non-healthcare professionals or even be self-sampled. Recent studies suggest that the sensitivity of saliva-based SARS-CoV-2 RNA detection methods seem to be comparable to or better than that of nasopharyngeal swabs. Conclusion: This paper reviews the role of saliva in the diagnosis of covid-19 infection, with special emphasis on its advantages, limitations and clinical implications.