mRNA vaccines are immunogenic in K18-hACE2 transgenic mice. We next evaluated the mRNA-1273 and mRNA-1273.351 vaccines in K18-hACE2 transgenic mice, which are highly susceptible to severe infection and disease after intranasal inoculation by many SARS-CoV-2 strains (22) including isolates containing or lacking mouse-adapting mutations, such as N501Y (17). Here, KRT18 is linked to infection.