ACE2 and infection: ACE2-Ig could potently inhibit D614G- and Omicron-pseudotyped virion infections with 50% inhibitory concentrations (IC50s) of 65.96 ng/mL and 26.09 ng/mL, respectively, indicating that the Omicron is still or even more sensitive to inhibition by ACE2-Ig (Fig. 1C).