Saliva as a diagnostic specimen for detecting SARS-COV-2

COVID-19 caused by SARS-CoV-2 is a serious and potentially deadly disease with an incidence rate of 36.1 per 100 000 population in the EU/EEA as of 25 March [Coronavirus disease 2019 (COVID-19) pandemic: increased transmission in the EU/EEA and the UK – seventh update Rapid Risk Assessment, ECDC, 15.03.2020]. More than 80 000 new cases are reported worldwide each day [Situation update worldwide, as of 19 April 2020, ECDC, 19.04.2020]. Early diagnosis and isolation of the infected people will play an important role in stopping the further escalation of this pandemic. At the moment, application of nasopharyngeal swabs is the most common method for specimen collection. However, this method requires qualified personnel to collect the specimen, thus exposing the medical stuff to a higher risk of infection, and shortages of swabs are frequently reported. Due to these factors, the nasopharyngeal swab collection method is causing financial and logistic burden on healthcare systems. Additionally, nasopharyngeal specimen collection method causes serious discomfort to the patients. Besides, there are several contraindications, such as coagulopathy or anticoagulant therapy and significant nasal septum deviation. Clearly, there is a need for a simple, less invasive method that also reduces the risk to healthcare personnel. One candidate for specimen collection is saliva. Several scientific papers have been published on the possible use of saliva as a specimen for COVID-19 diagnosis. However, until now no systematic review or meta-analysis have been conducted to estimate the true potentials of saliva for COVID-19 diagnosis. Our aim is to conduct a systematic review and meta-analysis on the available relevant literature in order to estimate the reliability and consistency of saliva specimens for COVID-19 diagnostics.