Moderna announced that mRNA-1647, its cytomegalovirus (CMV) vaccine candidate, failed to meet efficacy in a pivotal Phase 3 trial and the company will stop most development of the program. The readouts showed limited protective effect in the target populations, prompting an immediate strategic pause on the program. Moderna framed the decision as a reprioritization of resources amid disappointing Phase 3 efficacy. The failure removes what had been one of Moderna’s leading non-COVID mRNA hopes and adds pressure on management to replace anticipated revenue streams. Moderna executives have acknowledged the disappointment publicly and signaled the company will focus on other pipeline assets and indications. Investors and analysts are reassessing near-term expectations for Moderna’s post‑pandemic portfolio expansion.