ACE2 and COVID-19: This paradoxical higher immune response with poorer viral clearance may be related to the unique trait of COVID-19, i.e., higher affinity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RBD for ACE2 expressed on endothelial cells, which increases infectivity within the vascular compartment, and when coupled with significant macrophage/monocyte activation, will trigger coagulation pathways, generating severe microvascular thrombosis as demonstrated in the lungs in COVID-19 autopsies.