Andusomeran (CX-038839 Omicron XBB.1.5): A Comprehensive Report on the Monovalent COVID-19 mRNA Vaccine

1. Executive Summary

CX-038839 Omicron (XBB.1.5), generically known as Andusomeran and marketed under brand names such as Spikevax XBB.1.5, is a monovalent messenger RNA (mRNA) vaccine developed by Moderna. It is designed to elicit a protective immune response against the XBB.1.5 subvariant of the SARS-CoV-2 Omicron lineage, which was a predominant circulating strain during its development period.[1] The vaccine employs nucleoside-modified mRNA technology, encoding the prefusion-stabilized spike (S) glycoprotein of the SARS-CoV-2 Omicron XBB.1.5 variant, encapsulated within lipid nanoparticles (LNPs) to facilitate cellular uptake and antigen expression.[1]

Preclinical studies, primarily in murine models, demonstrated that XBB.1.5-adapted mRNA vaccines induce robust neutralizing antibody responses against the XBB.1.5 variant and show some cross-neutralization against related XBB sublineages and, to a lesser extent, more divergent variants like JN.1.[4] Clinical trials, including Phase 2/3 studies (e.g., NCT04927065) and real-world effectiveness studies, have confirmed the immunogenicity of Andusomeran, showing significant increases in neutralizing antibody titers against XBB.1.5 post-vaccination and providing protection against COVID-19-related hospitalization and medically attended illness.[5] The safety profile of Andusomeran is consistent with that of previous Moderna mRNA COVID-19 vaccines, with common solicited adverse events being mild to moderate and transient.[5]