ACE2 and infection: To evaluate the antiviral effect of EGCG in a more relevant cell type, we generated A549 cells stably expressing human ACE2, the receptor for SARS-CoV-1 and SARS-CoV-2, and isolated a clone (B9) with high levels of ACE2 expression and enhanced susceptibility to SARS-CoV-2 S pseudoparticle infection, but not HCoV-OC43 infection which does not require ACE2 as a receptor (Fig. S1a–e).