Oral saliva and COVID-19

•ACE-2 is a critical COVID-19 receptor can be found in salivary gland epithelial cells.•COVID-19 can be transmitted through saliva droplets.•SARS-CoV-2 might induce acute and chronic sialadenitis.•Salivary diagnostics testing can be a convenient tool for early-diagnosis of Covid-19. Outbreak pneumonia announced in Wuhan, China, in December 2019, had its causative factor classified as a new coronavirus (SARS-CoV-2). Since saliva can host several viruses including SARS-CoV-2, the transmission chance of viruses through saliva, particularly those causing respiratory infections, is unavoidable. COVID-19 can be detected through salivary diagnostic testing which has lots of advantages for medical care professionals and patients. It should be noted that not only does saliva offer an ecological niche for the colonization and development of oral microorganisms, but it also prevents the overgrowth of particular pathogens such as viral factors. The aim of this study is to gather all the information about saliva and its association with COVID-19 for the whole health care professionals across the world.