ACE2 and infection: This prevented infection with SARS-CoV-2 and the Omicron BA.2 variant in vitro and in vivo.141 Notably, HR121 vaccination produced potent nAb responses in human ACE2 transgenic mice, Syrian golden hamsters, and rhesus monkeys, providing nearly complete protection against ancestral SARS-CoV-2 infection, as well as effective protection against the Omicron BA.2 variant infection in Syrian golden hamsters.141 Notably, HR121, which possesses the HR1 groove, is a better vaccine antigen than HR12 that designed with the intact 6-HB scaffold.