mRNA-1273.231

mRNA-1273.231 is a bivalent, investigational mRNA-based COVID-19 vaccine booster developed by Moderna. It encodes for the spike protein of both the Omicron BA.4/BA.5 and XBB-lineage (specifically XBB.1.5/XBB.1.9.1) variants of SARS-CoV-2, aiming to broaden immune protection against circulating and emerging Omicron subvariants[7][8]. The vaccine uses lipid nanoparticle technology to deliver messenger RNA encoding these spike proteins into host cells, where they are translated into antigenic proteins that stimulate an immune response, including neutralizing antibodies[7][8]. Clinical studies have shown that mRNA-1273.231 induces high binding and neutralizing antibody responses against multiple Omicron subvariants when used as a booster in individuals previously vaccinated with other COVID-19 vaccines[7][1]. Its safety profile is consistent with earlier Moderna COVID-19 vaccines[1].