NCT06686654

Study of a Human Metapneumovirus/Respiratory Syncytial Virus mRNA Vaccine Candidate Encapsulated in a Lipid Nanoparticle-based Formulation in Adults Aged 60 Years and Older

Active, enrolled Phase 1, PHASE2 Last updated 11 December 2025

What this trial tests

Phase 1, PHASE2 trial testing Investigational hMPV/RSV vaccine in Human Metapneumovirus Immunization in 1,530 participants. Participants enrolled and being followed up; not accepting new ones.

Timeline

11 November 2024

Primary endpoint
18 January 2027

18 January 2027

Quick facts

Lead sponsor	Sanofi Pasteur, a Sanofi Company
Phase	Phase 1, PHASE2
Status	Active, enrolled
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	quadruple
Primary purpose	prevention
Enrollment	1,530
Start date	11 November 2024
Primary completion	18 January 2027
Estimated completion	18 January 2027
Sites	24 locations across United States

Drugs / interventions tested

• Investigational hMPV/RSV vaccine — full drug profile →
• Investigational hMPV vaccine (monovalent) — full drug profile →
• Investigational RSV vaccine (monovalent) — full drug profile →
• Licensed RSV Vaccine — full drug profile →
• Placebo
• Investigational RSV+hMPV vaccine — full drug profile →

Conditions studied

• Human Metapneumovirus Immunization — all drugs for Human Metapneumovirus Immunization →
• Respiratory Syncytial Virus Immunization — all drugs for Respiratory Syncytial Virus Immunization →

Sponsor

Sanofi Pasteur, a Sanofi Company — full company profile →

Who can join

60 and older, any sex, with Human Metapneumovirus Immunization or Respiratory Syncytial Virus Immunization. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

The aim of this study is to evaluate the safety and immunogenicity of a human metapneumovirus (hMPV) / respiratory syncytial virus (RSV) mRNA vaccine candidate encapsulated in a lipid nanoparticle (LNP) based formulation (hereafter referred to as hMPV/RSV vaccine) for the prevention of lower respiratory tract disease (LRTD) caused by hMPV and/or RSV among adults aged 60 years and older.

The study will also evaluate the safety and immunogenicity of a booster vaccination using a bivalent hMPV/RSV mRNA vaccine candidate (hereafter referred to as RSV+hMPV mRNA vaccine candidate).

Overall, the study is designed to address the following goals:

* Assess the safety profile of the candidate formulations.
* Describe the immunogenicity profile of the candidate formulations.
* Select the vaccine formulations (dose) for future development.
* Assess the safety and immunogenicity of a booster vaccination with the RSV + hMPV mRNA vaccine candidate administered 12 months after primary vaccination with a licensed RSV vaccine.

The study duration is as follows:

-Six months each for the Sentinel and Main Cohorts; up to 12 months for the Expansion Cohort, and 6 additional months for the Booster Cohort

Treatment duration:

* Stage 1 Sentinel Cohort: 1 intra-muscular (IM) injection. Participants will be followed for 6 months post vaccination
* Stage 1 Main Cohort: 1 IM injection. Participants will be followed for 6 months post vaccination
* Stage 2 Expansion Cohort: 1 IM injection. Participants in the licensed RSV vaccine arm will be followed for 12 months post-vaccination; the remainder of the participants will be followed up to 8 months post-vaccination
* Stage 2 Booster Cohort: 1 IM injection 12 months post-primary vaccination. Participants will be followed for 6 months post-booster vaccination

Publications & conference data

7 peer-reviewed publications reference this trial (live from Europe PMC):

1. Human metapneumovirus: pathogenesis, epidemiology, diagnostic technologies, and potential intervention strategies.
   Gao G, Lin R, Ma D. · · 2025 · cited 2× · PMID 41239485 · DOI 10.1186/s12985-025-02983-5
2. A Systematic Review of Clinical Trials Using mRNA Vaccines for Infectious Diseases other than COVID-19.
   Sofroniou A, Ridley A. · · 2025 · cited 2× · PMID 40756606 · DOI 10.3389/bjbs.2025.14557
3. Concerns and challenges in clinics-guided nanovaccines design and applications.
   Gao Y, Hua S, Dong X, Zhang K, et al · · 2026 · cited 1× · PMID 41584362 · DOI 10.1016/j.apsb.2025.10.041
4. From bench to bedside: Unveiling the background and benefits of nanovaccines tested in clinics.
   Egorova VS, Kolesova EP, Voronina MV, Denisova ER, et al · · 2026 · PMID 41810466 · DOI 10.1016/j.ajps.2026.101116
5. Structural basis for childhood antibody recognition of the human metapneumovirus fusion protein.
   Khalil AM, Ghazi Esfahani B, Miller RJ, Huang J, et al · · 2025 · PMID 41455691 · DOI 10.1038/s41467-025-68021-8
6. mRNA therapeutics: Transforming medicine through innovation in design, delivery, and disease treatment.
   Ige MA, Ren X, Yang Y, Zhang H, et al · · 2025 · PMID 41210584 · DOI 10.1016/j.omtn.2025.102721
7. Respiratory viral infections in lung transplantation: Recent advances in epidemiology, clinical impact, and therapeutic approaches.
   Bahakel H, Danziger-Isakov L. · · 2025 · PMID 40893635 · DOI 10.1016/j.jhlto.2025.100362