SARS-CoV-2 Omicron virus causes attenuated disease in mice and hamsters

The recent emergence of the Omicron variant has raised concerns of escape from protection by vaccines and therapeutic antibodies. A key test for potential countermeasures against the variant is their activity in preclinical rodent models of respiratory tract disease. Here, we evaluated the ability of several B.1.1.529 isolates to cause infection and disease in immunocompetent and human ACE2 (hACE2)-expressing mice and hamsters.