One advantage of mRNA vaccines is the ability to modify them rapidly and efficiently to target new variants. This year, Moderna developed and tested two updated, bivalent vaccines that target the Beta variant and Omicron variant, respectively, of the coronavirus SARS-CoV-2 (as well as the ancestral strains).

Data from two phase 2/3 studies indicated that booster doses of the updated vaccines generated better neutralizing antibody responses than did boosters with the original mRNA-1273 vaccine. Further research is needed to definitively evaluate efficacy and real-world effectiveness — but these studies suggest that updating the vaccines is beneficial as the virus evolves.

Original references: https://doi.org/10.1038/s41591-022-02031-7; https://doi.org/10.1056/NEJMoa2208343