Protective activity of mRNA vaccines against ancestral and variant SARS-CoV-2 strains

Although mRNA vaccines encoding the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) prevent COVID-19, the emergence of new viral variants jeopardizes their efficacy. Here, we assessed the immunogenicity and protective activity of historical (mRNA-1273, designed for Wuhan-1 spike protein) or modified (mRNA-1273.351, designed for B.1.351 spike protein) Moderna mRNA vaccines in 129S2 and K18-hACE2 mice. Mice were...