ACE2 and infection: In the human eye organoid, the limbus is most infected by the virus, whereas the central cornea is less susceptible to infection.105 In human airway organoids, the virus mainly infects and replicates in the basal epithelial cells,106 which co-express ACE2 and TMPRSS2, which are major portals for the infection and transmission of SARS-CoV-2,112 while the virus is not detected in other cell types, such as cilia and club cells.