Moderna announced that its cytomegalovirus (CMV) mRNA vaccine mRNA‑1647 failed to meet the primary efficacy endpoint in a pivotal Phase III trial and is halting most development of the program. The company said efficacy ranged from single‑digit to low‑twenties percentage points and that the result fell well short of expectations. The readout represents a significant setback for Moderna’s post‑COVID vaccine ambitions; the CMV candidate had been viewed as a potential multibillion‑dollar franchise and a key commercial diversification beyond its COVID program. Moderna said it will stop broad development of mRNA‑1647 and reassess resources across its vaccine portfolio and oncology programs. Analysts and investors flagged the trial miss as intensifying pressure on Moderna’s respiratory and vaccine pipeline and accelerating cost‑control measures. The company will shift focus to other clinical assets, including cancer vaccine efforts highlighted at recent conferences.