ACE2 and infection: Many studies have reported on new receptors for SARS-CoV-2, but most receptors are co-receptors for ACE2, such as host proteases transmembrane proteases serine 2 (TMPRSS2)14 and Neuropilin-1 (NRP-1).8,22 The only known non-ACE2 receptors are AXL21 and CD147.24 However, AXL and CD147 are mainly expressed in lung cells and monocytes, respectively, which cannot explain the infection of other tissues by SARS-CoV-2.