Saliva as a Potential SARS-CoV-2 Reservoir: What is Already Known? A Systematic Review

Introduction: Saliva is a reservoir for biologic indicators and has a diverse microflora, which is critical particularly for coronavirus disease 2019 (COVID-19) transmission. Notwithstanding, saliva also could be applied as a noninvasive method to COVID-19 diagnosis and disease evolution monitoring. The objective of this systematic review is to summarize the main findings regarding to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection repercussion in saliva and/or salivary glands, addressing the following questions: What has been published regarding to the presence and implications of COVID-19 in saliva or salivary glands? and What are the researchers’ main results and conclusions?. Materials and Methods: A total of 31 published articles were included (27 research articles and 4 case reports). PubMed, Embase, Scopus, Web of Science, and Google Scholar databases were searched till August 2020. The terms COVID-19, novel coronavirus, and SARS-CoV-2 were combined with the keywords salivary gland, saliva, sialadenitis, parotid gland, sublingual gland submandibular gland, salivary gland disease, and minor salivary gland using the Boolean operator “AND.” Results: In this study, researchers’ main results and conclusions were exposed in tables. The main subjects of the articles were detection and viral load of SARS-CoV-2 in saliva, the influence of mouthwashes in SARS-CoV-2, and the presence of SARS-CoV-2 in aerosols. Conclusion: Although deep throat saliva may be used as a diagnostic tool to SAR-CoV-2 diagnosis, researchers found that the viral load in saliva is lower than in respiratory secretions.