CREATED a new SARS-COV-2 (Omicron S): MORTALITY rate of 80% (in mice)

… SARS-CoV-2 Omicron variant (BA.1) is highly transmissible, even in fully vaccinated individuals

… causes attenuated disease compared with other major viral variants recognized to date

… We generated chimeric recombinant SARS-CoV-2

… encoding the S gene of Omicron in the backbone of an ancestral SARS-CoV-2 isolate

… and compared this virus with the naturally circulating Omicron variant

… The Omicron S-bearing virus robustly escapes vaccine-induced humoral immunity

… efficiently replicates in cell lines and primary-like distal lung cells

… In K18-hACE2 mice, while Omicron causes mild, non-fatal infection

… the Omicron S-carrying virus inflicts severe disease with a mortality rate of 80%