These studies have also provided insights into the molecular mechanisms of viral infection and replication relevant for drug repurposing (Si et al., 2021), as well as different cell targets in addition to AT2 cells, including HTII-280- ACE2+ cells (Zhang et al., 2020), or lung microvascular endothelial cells (Thacker et al., 2021). Here, ACE2 is linked to viral infectious disease.