Yokota I, Sakurazawa T, Sugita J, Iwasaki S, Yasuda K, Yamashita N, Fujisawa S, Nishida M, Konno S, Teshima T. Performance of Qualitative and Quantitative Antigen Tests for SARS-CoV-2 Using Saliva. Infect Dis Rep. 2021 Aug 24;13(3):742-747.