🧬 CMV Vaccine Tracker Dashboard
Updated July 2026. Tracking cytomegalovirus (CMV) vaccine development to prevent congenital CMV infection, the leading infectious cause of birth defects worldwide. CMV affects 1 in 200 babies (0.5-0.7% of all births), causing permanent disabilities including hearing loss, vision impairment, intellectual disability, and cerebral palsy. Major setback: Moderna announced on October 22, 2025 that its lead candidate mRNA-1647 did not meet its primary endpoint in the Phase 3 CMVictory trial — vaccine efficacy was 6–23% depending on case definition, well below target — and the company has discontinued its congenital CMV development program. Moderna continues to evaluate mRNA-1647 in a Phase 2 trial for CMV reactivation in bone marrow transplant patients (expected to end August 2026). GSK's gB/MF59 remains the most advanced congenital-prevention candidate. This tracker monitors the complete CMV vaccine pipeline targeting maternal immunization, transplant recipients, and congenital infection prevention.
CMV Vaccines by Development Phase
1
Phase 3 Trials (post-mRNA-1647 failure)
1 in 200
Babies Born with CMV
🔬 Phase 3 Clinical Trials - LEADING CANDIDATES!
Technology
mRNA-LNP (6 antigens)
Phase 3 Trial
CMVictory (NCT05085366)
Phase 3 Result
6–23% efficacy — missed endpoint
Phase 3 Size
~7,454 women, 13 countries
Announcement
October 22, 2025
Phase 3 Outcome (Oct 22, 2025): Moderna announced that the pivotal Phase 3 CMVictory trial (NCT05085366) of mRNA-1647 did not meet its primary efficacy endpoint of preventing CMV infection in CMV-seronegative women aged 16–40. Vaccine efficacy against primary CMV infection ranged from 6% to 23% depending on the case definition — well below the target. The trial enrolled approximately 7,454 women across ~300 sites in 13 countries, representing the largest efficacy study for a CMV vaccine to date. The vaccine was well-tolerated but did not confer meaningful protection.
Program Status: Moderna has discontinued the congenital CMV development program for mRNA-1647. The company will continue evaluating mRNA-1647 in an ongoing Phase 2 trial (~224 patients) assessing suppression of CMV reactivation in bone marrow transplant recipients; this trial is expected to complete in August 2026. Full CMVictory results are still forthcoming and will be shared with the scientific community.
Background: mRNA-1647 encodes six CMV antigens — glycoprotein B (gB), the pentameric complex (gH/gL/UL128/UL130/UL131A), and pp65 — delivered as an mRNA-lipid nanoparticle formulation on a three-dose schedule (0, 2, 6 months). Prior Phase 2 CMVictory data (NEJM 2024) had shown ~50% efficacy against primary CMV infection in a 6,500-participant cohort, which supported advancement into Phase 3.
Technology
Recombinant gB + MF59
Target Population
Postpartum women, transplant recipients
Phase 2 Efficacy
43-50% vs primary infection
Development Time
20+ years (longest-studied)
Description: GSK's gB/MF59 consists of recombinant CMV glycoprotein B with MF59 adjuvant (squalene-based emulsion). Longest-studied CMV vaccine with 20+ years development. Multiple Phase 2 trials showed 43-50% efficacy preventing primary infection and reducing viral load in transplant recipients. Three-dose regimen. Phase 3 trials ongoing in postpartum women and transplant recipients. Well-tolerated safety profile. Represents proven protein subunit approach used in licensed vaccines.
🧬 Phase 2 & Earlier Development
Phase 2 Candidates (3): Replication-defective CMV vaccines, DNA vaccines, VLP platforms. Phase 1 (4): Next-generation mRNA vaccines, viral vectors, novel adjuvant combinations. Preclinical (5): Self-amplifying RNA, nanoparticle vaccines, T cell-focused vaccines, therapeutic vaccines for transplant patients, broad herpesvirus vaccines.