ACE2 and infection: ACE2 is not only expressed on lung alveolar epithelial cells but also on enterocytes of the small intestine, in arterial and venous endothelial cells, and arterial smooth muscle cells in all organs studied, testis, heart, kidney, liver, brain, and thyroid gland.19–21 Furthermore, viremia after lytic infection of lung epithelium is documented by reports that measured both infectious particles and/or viral RNA in blood, whereby the virus load in blood correlated strongly with disease severity.22