Phase 2b Study of a Respiratory Syncytial Virus and Human Metapneumovirus (RSV+HMPV) Protein Vaccine Candidate in Adults 60 Years of Age and Older

A Phase 2b, Randomized, Placebo-controlled, Observer-blind Study in Adults 60 Years of Age and Older to Evaluate the Efficacy, Safety, and Immunogenicity of a Bivalent Protein Vaccine Candidate Against Respiratory Syncytial Virus (RSV) and Human Metapneumovirus (HMPV)

Study VCA25397 is a Phase 2b, observer-blind, randomized, placebo-controlled, parallel, case-driven proof of concept study that will enroll approximately 8000 adults aged 60 years and older to assess the clinical efficacy, safety, and immunogenicity of a single IM (intramuscular) injection of the bivalent RSV+HMPV protein vaccine candidate.

The study will include a Safety Lead-in Cohort that will be enrolled first and will comprise 200 participants aged 60 years and older randomized in a 1:1 ratio to receive either RSV+HMPV protein vaccine or placebo (100 participants per arm).

The enrollment of the Main Cohort will start after the completion of the ESDR (Early Safety Data Review), pending a positive outcome. For the Main Cohort, 7800 participants (3900 participants per arm) will be randomized in a 1:1 ratio to receive either RSV+HMPV protein vaccine or placebo.

Study Overview

• Status: Not yet recruiting
• Conditions: Healthy Volunteers; Respiratory Syncytial Virus; Human Metapneumovirus
• Intervention / Treatment: Biological: Placebo; Biological: Bivalent RSV+HMPV protein vaccine

• Study Type: Interventional
• Enrollment (Estimated): 8000
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Trial Transparency email recommended (Toll free for US & Canada); Phone Number: option 6 800-633-1610; Email: Contact-US@sanofi.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Aged 60 years or older on the day of inclusion
• Participants who, as determined by medical evaluation including medical history, physical examination, and clinical judgment of the Investigator are eligible for inclusion

Exclusion Criteria:

• Known/suspected immunodeficiency; immunosuppressive therapy/immunomodulators in past 6 months; long-term systemic corticosteroids (eg, prednisone for more than 2 weeks in past 3 months); history of immune-mediated neurological disease. Of note, persons living with stable HIV are not excluded
• Known systemic hypersensitivity to any of the study intervention components or history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances
• Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with study conduct or completion
• Previous history of Guillain-Barré Syndrome (GBS)
• Previous vaccination against RSV and/or HMPV (with a licensed or investigational vaccine either as a monovalent vaccine or any combination of the antigens) or previous receipt of RSV and/or HMPV monoclonal antibody

The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Safety Lead-in Cohort - Experimental; Single administration of IM (intramuscular) injection of the bivalent RSV+HMPV protein vaccine candidate	Biological: Bivalent RSV+HMPV protein vaccine; IM injection; Other Names: RPF08203
Placebo Comparator: Safety Lead-in Cohort - Placebo; Single administration of matching placebo	Biological: Placebo; IM injection
Experimental: Main Cohort - Experimental; Single administration of IM (intramuscular) injection of the bivalent RSV+HMPV protein vaccine candidate	Biological: Bivalent RSV+HMPV protein vaccine; IM injection; Other Names: RPF08203
Placebo Comparator: Main Cohort - Placebo; Single administration of matching placebo	Biological: Placebo; IM injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Occurrence of the first episode of RSV-LRTD (Lower Respiratory Tract Disease)	From 14 days to 12 months after vaccination
Occurrence of the first episode of HMPV-LRTD	From 14 days to 12 months after vaccination

Secondary Outcome Measures

Outcome Measure	Time Frame
Occurrence of the first episode of RSV-LRTD and/or HMPV-LRTD	From 14 days to 12 months after vaccination
Occurrence of the first episode of RSV-ARD (Acute Respiratory Disease) and/or HMPV-ARD	From 14 days to 12 months after vaccination
Occurrence of the first episode of severe RSV-LRTD and/or severe HMPV-LRTD	From 14 days to 12 months after vaccination
Occurrence of the first episode of RSV-URTD and/or HMPV-URTD	From 14 days to 12 months after vaccination
RSV A, RSV B, and HMPV A, HMPV B serum nAb titers in a subset of participants	At pre-vaccination and 8 days, 28 days, 6 months and 12 months post- vaccination
Presence of immediate unsolicited systemic AEs (Adverse Events)	Within 30 minutes after vaccination
Presence of solicited injection site and systemic reactions in a subset of participants	Up to 7 days after vaccination
Presence of unsolicited AEs reported	Up to 27 days after vaccination
Presence of MAAEs (Medically Attended Adverse Events)	Within 6 months after vaccination
Presence of SAEs (Serious Adverse Events) and AESIs (Adverse Event of Special Interest)	Within 6 months after vaccination
Presence of related SAEs, related AESIs, and fatal SAEs	Up to 12 months post-vaccination
Presence of out-of-range biological test results in a subset of participants	7 days after vaccination

Collaborators and Investigators

• Sponsor: Sanofi

Study record dates

Study Major Dates

• Study Start (Estimated): September 7, 2026
• Primary Completion (Estimated): July 3, 2028
• Study Completion (Estimated): July 3, 2028

Study Registration Dates

• First Submitted: September 3, 2026
• First Submitted That Met QC Criteria: September 3, 2026
• First Posted (Actual): September 9, 2026

Study Record Updates

• Last Update Posted (Actual): September 9, 2026
• Last Update Submitted That Met QC Criteria: September 3, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: VCA25397; 2026-526177-42 (Registry Identifier: CTIS); U1111-1337-5133 (Registry Identifier: ICTRP)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No