Moderna announced that its mRNA cytomegalovirus vaccine mRNA‑1647 failed to meet the primary efficacy endpoint in a large Phase III pivotal trial and will largely stop further development of the program. The CMVictory study produced efficacy well below expectations, prompting the company to pause most CMV work and redirect resources toward oncology and other pipeline priorities. The failed readout represents a major setback for Moderna, which had positioned CMV as a potential multibillion‑dollar product after COVID‑19. Company statements and market reports indicate broader restructuring and reprioritization of R&D spend. The result has implications for investor sentiment toward mRNA platforms beyond infectious disease and raises questions about antigen selection, dosing, and correlates of protection for complex congenital infection targets. Moderna’s leadership signaled continued commitment to mRNA-based therapeutics in oncology despite the setback. The CMV failure will trigger re‑examination of late‑stage vaccine strategies across the industry and could alter partner, regulatory and reimbursement dynamics for future mRNA vaccine programs.