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.
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%.
Imagine how hard the US will be bashing China if it said the University of Wuhan instead of the University of Boston.
Anyway. Keep in mind these results are for mice and not primates.
One potential limitation of our study is the use of K18-hACE2 mice for pathogenesis studies instead of the primate models that have more similarities with humans

