Study of Different Formulations of Vaccines Encoding the RSV Monovalent Antigen or the Flu H5 Antigen in Participants 18 to 49 Years of Age

May 5, 2026 updated by: Sanofi

A Phase 1, Randomized, Multi-center Study to Evaluate the Safety and Immunogenicity of Different Formulations of Vaccines Encoding the RSV Monovalent Antigen or the Flu H5 Antigen in Healthy Participants 18 to 49 Years of Age

The purpose of this study is to evaluate the safety and immunogenicity of different formulations of vaccines encoding the RSV monovalent antigen or the Flu hemagglutinin subtype 5 (H5) antigen in healthy participants aged 18 to 49 years.

The total duration of study participation for each participant varies by stage and treatment arm.

Stage 1:

  • For Arm 1, Arm 2, and Arm 3 the duration of study participation will be approximately 7 months for each participant.
  • For Arm 4, Arm 5, and Arm 6 the duration of study participation will be approximately 6 months for each participant.

Stage 2: For all arms, the duration of study participation will be approximately 7 months for each participant.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

570

Phase

  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Sanofi Trial Transparency Email Recommended (Toll free for US and Canada)
  • Phone Number: Opt. 6 800-633-1610
  • Email: contact-us@sanofi.com

Study Locations

  • Australia
    • Queensland
      • Griffith, Queensland, Australia, 4222
        • Recruiting
        • Site # 0361002
      • Herston, Queensland, Australia, 4006
        • Recruiting
        • Site # 0361001
      • Morayfield, Queensland, Australia, 4506
        • Recruiting
        • Site # 0361003
      • Sippy Downs, Queensland, Australia, 4556
        • Recruiting
        • Site # 0361005
      • South Brisbane, Queensland, Australia, 4104
        • Recruiting
        • Site # 03610004
      • Taringa, Queensland, Australia, 4068
        • Recruiting
        • Site # 036006

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Aged 18 to 49 years on the day of inclusion
  • A female participant is eligible to participate if she is not pregnant or breastfeeding and of the following conditions applies:
  • Is of NCBP (Non-Child-Bearing Potential). To be considered of NCBP, a female must be post-menopausal for at least 1 year, or surgically sterile. OR
  • Is of CBP (Child-Bearing Potential) and uses an effective contraceptive method or abstinence from at least 4 weeks prior to study intervention administration until at least 12 weeks after the last study intervention administration.

Exclusion Criteria:

• Any condition which, in the opinion of the Investigator, might interfere with the evaluation of the study objectives

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Sequential Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Stage 1, Arm 1
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu Investigational Medical Product (IMP) 1
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 1, Arm 2
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu IMP 2
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 1, Arm 3
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu IMP 3
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 1, Arm 4
Participants will receive a single IM (Intramuscular) injection on day 1 of the RSV vaccines according to their randomization schedule.
Biological: RSV IMP 4
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 1, Arm 5
Participants will receive a single IM (Intramuscular) injection on day 1 of the RSV vaccines according to their randomization schedule.
Biological: RSV IMP 5
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 1, Arm 6
Participants will receive a single IM (Intramuscular) injection on day 1 of the RSV vaccines according to their randomization schedule.
Biological: RSV IMP 6
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 2, Arm 1
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu IMP 7
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 2, Arm 2
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu IMP 8
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 2, Arm 3
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu IMP 9
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 2, Arm 4
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu IMP 10
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 2, Arm 5
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu IMP 11
Suspension for injection. Route of administration: Intramuscular (IM) injection
Experimental: Stage 2, Arm 6
Participants will receive a single IM (Intramuscular) injection on day 1 and day 22 of the H5 Flu vaccines according to their randomization schedule.
Biological: H5 Flu IMP 12
Suspension for injection. Route of administration: Intramuscular (IM) injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Presence of any unsolicited systemic Adverse Events (AEs) reported within 30 minutes after vaccination
Time Frame: On Day 1
On Day 1
Presence of solicited injection site reactions (ie, injection site pain, injection site erythema, injection site swelling, pre-listed in participant's diary and in the eCRF (electronic case report form)) occurring through 7 days after each vaccination
Time Frame: Day 1 through day 8
Day 1 through day 8
Presence of solicited systemic reactions (ie, fever, headache, and only new or worsened fatigue, myalgia, arthralgia, and chills pre-listed in the participant's diary and in the eCRF) occurring through 7 days after each vaccination
Time Frame: Day 1 through day 8
Day 1 through day 8
Presence of unsolicited AEs reported through 20 days after the first vaccination and after the second vaccination for IMPs with the Flu H5 antigen
Time Frame: Day 1 through day 21
Day 1 through day 21
Presence of unsolicited AEs reported through 28 days after vaccination for IMPs with the RSV antigen
Time Frame: Day 1 through day 29
Day 1 through day 29
Presence of SAEs (Serious Adverse Events) and AESIs (Adverse Events of Special Interest) throughout the study (ie, through 6 months after vaccination)
Time Frame: SAE: Screening day through day 202 (IMPs containing Flu H5 antigen), Screening day through day 181 (IMPs containing RSV antigen); AESI: Day 1 through day 202 (IMPs containing Flu H5 antigen), Day 1 through day 181 (IMPs containing RSV antigen)
SAE: Screening day through day 202 (IMPs containing Flu H5 antigen), Screening day through day 181 (IMPs containing RSV antigen); AESI: Day 1 through day 202 (IMPs containing Flu H5 antigen), Day 1 through day 181 (IMPs containing RSV antigen)
Presence of out-of-range biological test results (including shift from baseline values) through 7 days after each vaccination
Time Frame: Screening through day 8
Screening through day 8
Presence of AEs leading to study discontinuation throughout the study (ie, through 6 months after vaccination)
Time Frame: Screening through day 202 (IMPs containing Flu H5 antigen), Screening through day 181 (IMPs containing RSV antigen)
Screening through day 202 (IMPs containing Flu H5 antigen), Screening through day 181 (IMPs containing RSV antigen)
RSV A and RSV B serum nAb (neutralizing antibodies) titers at pre-vaccination and 28 days post-vaccination in all participants receiving IMPs with the RSV antigen
Time Frame: Day 1 and day 29
Day 1 and day 29
Flu H5 antibody (Ab) titer measured by hemagglutination inhibition (HAI) at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22 and day 43
Day 1, day 22 and day 43
Hemagglutination Inhibition (HAI) geometric mean titer ratio at 21 and 42 days post-vaccination relative to pre-vaccination for all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22 and day 43
Ratio of post-vaccination to pre-vaccination hemagglutination inhibition (HAI) antibody titers, calculated as Day 22/Day 1 and Day 43/Day 1.
Day 1, day 22 and day 43
Seroconversion rate based on Hemagglutination inhibition (HAI) antibody titers at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22 and day 43
Day 1, day 22 and day 43
Proportion of participants with Hemagglutination Inhibition (HAI) antibody titer ≥40 at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22, and day 43
Day 1, day 22, and day 43
Proportion of participants with detectable HAI antibody titer ≥10 at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22, and day 43
Day 1, day 22, and day 43

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Geometric mean neutralizing antibody titers measured by Neutralization Assay (NT) at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22, and day 43
Day 1, day 22, and day 43
Neutralizing antibody titer ratio at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22, and day 43
Ratio of post-vaccination to pre-vaccination neutralizing antibody titers, calculated as Day 22/Day 1 and Day 43/Day 1 using a validated neutralization (NT) assay.
Day 1, day 22, and day 43
Proportion of participants with neutralizing antibody titers ≥20, ≥40, and ≥80 at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22, and day 43
Day 1, day 22, and day 43
Proportion of participants with detectable neutralizing antibody titers ≥10 at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22, and day 43
Day 1, day 22, and day 43
Proportion of participants with ≥2-fold and ≥4-fold increase in neutralizing antibody titers at pre-vaccination and 21 and 42 days post-vaccination in all participants receiving IMPs with the Flu H5 antigen
Time Frame: Day 1, day 22, and day 43
Day 1, day 22, and day 43

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sanofi

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 15, 2026

Primary Completion (Estimated)

April 4, 2027

Study Completion (Estimated)

April 4, 2027

Study Registration Dates

First Submitted

March 31, 2026

First Submitted That Met QC Criteria

March 31, 2026

First Posted (Actual)

April 8, 2026

Study Record Updates

Last Update Posted (Actual)

May 8, 2026

Last Update Submitted That Met QC Criteria

May 5, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • VAV00053
  • U1111-1322-6386 (Other Identifier: WHO UTN)

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

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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