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Lower Respiratory Tract DiseasePhase 1VXB251-001NCT07295028

Study of an RSV-hMPV-PIV3 Trivalent Vaccine Candidate VXB-251 in Older Adults

A Phase 1 study testing trivalent (RSV/hMPV/PIV3) vaccine candidate, bivalent (RSV/hMPV) unlicensed comparator and monovalent (RSV) unlicensed comparator in people with Lower Respiratory Tract Disease and Healthy Participants, run by Sanofi at 6 sites in Australia.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This study is being done to find out how safe and effective a new combined vaccine candidate, called VXB-251, is for older adults. The vaccine candidate is designed to protect against three common viruses that can cause respiratory tract infections: RSV (respiratory syncytial virus) hMPV (human metapneumovirus) PIV3… Read more about this study

Who is it for?
Ages 60 to 83 yearsHealthy volunteers can take part
What is being tested?
trivalent (RSV/hMPV/PIV3) vaccine candidate, bivalent (RSV/hMPV) unlicensed comparator and monovalent (RSV) unlicensed comparator
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
240 participants
Where
6 sitesAustralia
Study dates
17 Nov 2025to 24 Apr 2027
Phase
Phase 1
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 60 to 83 years
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • Males and females aged 60 to 83 years of age at inclusion.
  • Evidence of signed and dated participant informed consent form (PICF) prior to any study procedure, indicating that the subject has been informed of all pertinent aspects of the study.
  • Willingness and ability to comply with the planned study visits and calls, procedures, and restrictions for the duration of the study.
  • Good health, which allows for pre-existing well controlled and low impact chronic diseases, except for the diseases listed in the exclusion criteria. A disease is defined as well controlled and has a low impact if it did not require meaningful change in therapy or unplanned medical visit(s) in the previous 3 months and allows participant's primary responsibility for self-care and daily living activities.
  • Non-smoker or occasional smoker, defined as smoking less than 10 nicotine-containing cigarettes/ vapes/cigars/pipe fills per week.
  • Contraception and childbearing/conception potential: only female participants with non-childbearing potential will be included. Male participants in a relationship with a female partner of childbearing potential must be willing to use a double contraceptive method together with their female partner for at least 4 weeks before and 12 weeks after the IMP injection at Visit 2 (day 1).
  • Body mass index (BMI) ≥ 17.0 kg/m2 and ≤ 35.0 kg/m2.

Who cannot join

  • History of RSV, hMPV, and/or PIV3 infection affecting the participant and/or the participant's household in the previous 12 months.
  • History of autoimmune disease (AID) or possibly autoimmune disease (pAID) requiring therapeutic intervention, even if stable and well controlled, including, but not limited to, systemic lupus erythematosus, autoimmune arthritis/rheumatoid arthritis, Guillain-Barré syndrome, multiple sclerosis, Sjögren's syndrome, idiopathic thrombocytopenia purpura, glomerulonephritis, autoimmune thyroiditis, temporal arteritis, psoriasis, insulin-dependent diabetes mellitus, celiac disease.
  • Confirmed or suspected immunodeficiency, even if stable and well controlled.
  • Ongoing severe asthma. Other allergic diseases (e.g., allergic rhinitis, atopic dermatitis / eczema, mild to moderate asthma, food allergies) are allowed at the investigator's or delegate's discretion.
  • History of significant allergic reaction (e.g., anaphylaxis, hypersensitivity, angioedema) to medication or food or known allergy to vaccine, or any excipients in the formulation, and latex.
  • History of severe AE associated with vaccine administration.
Show all 26Show fewer
  • Ongoing disorders of coagulation, which contraindicate IM injections.
  • Donation or loss of ≥ 500 mL whole blood on the previous 2 months, and/or donation of plasma in the previous 1 week, and/or intention to donate blood or plasma during the study.
  • Positive serum test results indicating ongoing HIV, HBV and/or HCV infection, and/or documented ongoing HIV, HBV, or HCV infection.
  • Other poorly controlled and/or impactful chronic disease. A disease is defined as poorly controlled if it requires meaningful change in therapy and/or unplanned medical visit(s) in the previous 3 months. A disease is defined as impactful if, in the investigator's judgment, it meaningfully affects the participant's ability to manage self-care and/or activities of daily living.
  • Disease expected to prevent completion of the study (i.e. to rapidly deteriorate within the timeframe of the study).
  • Prior treatments.
  • Receipt of licensed RSV vaccine and/or enrollment in clinical trials(s) evaluating investigational RSV, hMPV, PIV3, and/or molecular clamp-based vaccine candidates at any time, unless it was documented that the participant received a placebo.
  • Other investigational drug or vaccine received in the previous 6 months.
  • Chemotherapy, radiotherapy, and/or other immunosuppressive medication (including biologics) received in the previous 6 months.
  • IgGs or any blood product received in the previous 3 months.
  • Systemic corticosteroids (oral/intravenous/IM) at doses equivalent to ≥ 20 mg prednisone per day received for ≥ 14 days, even if not consecutive, during the previous 3 months. Inhaled/nebulized, intra-articular, intra-bursal, skin, and eye topical corticosteroids are permitted.
  • Received or plan to receive licensed non-live vaccine(s) for the period starting 2 weeks before to 4 weeks after of the study IMP injection or licensed live vaccine(s) for the period starting from 4 weeks before to 4 weeks after the study IMP injection. Pandemic or emergency vaccines are always allowed as per country guidelines.
  • Clinically meaningful abnormal finding from physical examination, vital sign assessment, electrocardiogram (ECG), safety laboratory test results. If deemed appropriate, the investigator or delegate may repeat these assessments.
  • History of alcohol abuse in the previous year determined at the investigator's discretion.
  • History of recreational drug abuse in the previous year and/or positive test for drugs of abuse at Visit 2 (day 1), unless there is an explanation acceptable to the investigator (e.g., the participant has informed in advance that he/she consumed a prescription or over-the-counter product that contained the detected drug).
  • Intention to participate in any investigational drug/vaccine/medical device clinical trial at any time throughout the planned duration of this study.
  • Presence of tattoo, scarring, skin discoloration, or any other skin disturbances at the injection site which may interfere with effective assessment of the injection site.
  • Intention to move to a location that would prevent participating in the study until study end.
  • Any other reason which would prevent the participant from participating in the study or interfere with the participant's compliance with study procedures.
  • The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

Trial locations and contacts

6 sites in 1 country.

6 sites in 1 country

Australia6 sites

  • University of Sunshine Coast, South Bank

    Brisbane

  • Emeritus Research

    Camberwell

  • Momentum Clinical Research

    Darlinghurst

  • Veritus Research

    Melbourne

  • University of the Sunshine Coast

    Morayfield

  • University of the Sunshine Coast, Sippy Downs

    Sippy Downs

Other trials in Australia

About this study

Official title: A Phase 1 Randomized, Placebo- and Comparator-controlled (Bivalent and Monovalent Components), Observer-blind Study in Older Adults to Evaluate the Safety, Reactogenicity, and Immunogenicity of 3 Dose-levels of VXB-251 (Trivalent), for the Prevention of LRTD Caused RSV, hMPV, PIV3 and to Assess Immunological Interference and Cross-reactivity.

This study is being done to find out how safe and effective a new combined vaccine candidate, called VXB-251, is for older adults. The vaccine candidate is designed to protect against three common viruses that can cause respiratory tract infections:

  • RSV (respiratory syncytial virus)
  • hMPV (human metapneumovirus)
  • PIV3 (parainfluenza virus type 3)
Read more

Two components of this vaccine (RSV and hMPV) have already been tested in people before, as part of another study for a two-in-one vaccine. However, this is the first time that the PIV3 component and all three components together (RSV, hMPV, and PIV3) are being tested in people.

The vaccine candidate will be given as a single intramuscular injection. The study will also test unlicensed comparator vaccines and a placebo (a substance that looks like the real vaccine but doesn't contain any active ingredients) that target none, one or two of these viruses to see whether combining all three components affects safety or how well the immune system responds.

Read the detailed description

This is a multicenter randomized, placebo- and comparator-controlled, dose-ranging study to be conducted in Australia in older adults, aged 60 to 83 years, to evaluate the safety, reactogenicity, and immunogenicity of a trivalent RSV/hMPV/PIV3 vaccine candidate, VXB-251. All investigational medicinal products (IMPs) will be administered as a single 0.5 mL intramuscular injection on day 1.

Recruitment will be in 2 stages:

Stage 1 (N=10). Two cohorts, each of 5 participants, will be sequentially enrolled at a 4:1 ratio to receive:

  • Cohort 1: either a medium dose of the vaccine candidate or the placebo control,
  • Cohort 2: either a high dose of the vaccine candidate or the placebo control

At each enrolling site, at least 1 hour must elapse between IMP injection in the first sentinel and next IMP injection to monitor for hypersensitivity reactions and other fast-onset adverse events (AEs). The investigator or delegate will decide if and when the next sentinel can be vaccinated.

A Safety Monitoring Committee (SMC) will make recommendations on escalation from 1 sequential cohort to the next and progress from Stage 1 to Stage 2 based on 1-week safety and reactogenicity available data from the prior cohort.

Stage 2 (N=230). Participants will be concurrently assigned on day 1 (Visit 2) at an unequal ratio into 1 of 8 study groups and receive one of the following:

  • VXB-251 trivalent (RSV/hMPV/PIV3) vaccine candidate, low dose (N=30)
  • VXB-251 trivalent (RSV/hMPV/PIV3) vaccine candidate, medium dose (N=26)
  • VXB-251 trivalent (RSV/hMPV/PIV3) vaccine candidate, high dose (N=26)
  • VXB-241 bivalent (RSV/hMPV) unlicensed comparator (N=30)
  • VXB-213 monovalent (RSV) unlicensed comparator (N=30)
  • VXB-221 monovalent (hMPV) unlicensed comparator (N=30).
  • VXB-232 monovalent (PIV3) unlicensed comparator (N=30)
  • Placebo (N=28)

In Stage 1, the study will be open-label across cohorts and observer-blind within each cohort. In Stage 2, the study will be observer-blind.

The study duration for each participant will be 1 year.

Being tested
trivalent (RSV/hMPV/PIV3) vaccine candidate, bivalent (RSV/hMPV) unlicensed comparator, monovalent (RSV) unlicensed comparator, Biological/Vaccine: monovalent (hMPV) unlicensed comparator, monovalent (PIV3) unlicensed comparator
Keywords
RSV, hMPV, PIV3, Multipathogen respiratory virus vaccines

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • trivalent (RSV/hMPV/PIV3) vaccine candidateBiological

    VXB-251 low dose, single, IM injection.

  • trivalent (RSV/hMPV/PIV3) vaccine candidateBiological

    VXB-251 medium dose, single, IM injection.

  • trivalent (RSV/hMPV/PIV3) vaccine candidateBiological

    VXB-251 high dose, single, IM injection.

  • bivalent (RSV/hMPV) unlicensed comparatorBiological

    VXB-241 medium dose, single, IM injection.

  • monovalent (RSV) unlicensed comparatorBiological

    VXB-213 medium dose, single, IM injection.

  • Biological/Vaccine: monovalent (hMPV) unlicensed comparatorBiological

    VXB-221 medium dose, single, IM injection.

  • monovalent (PIV3) unlicensed comparatorBiological

    VXB-232 medium dose, single, IM injection.

  • PlaceboOther

    diluent, single, IM injection.

Study groups in NCT07295028
Study groupRoleWhat they receive
VXB-251, low doseExperimentalNot described
Receives: Biological: trivalent (RSV/hMPV/PIV3) vaccine candidate
VXB-251, medium doseExperimentalNot described
Receives: Biological: trivalent (RSV/hMPV/PIV3) vaccine candidate
VXB-251, high doseExperimentalNot described
Receives: Biological: trivalent (RSV/hMPV/PIV3) vaccine candidate
VXB-241ExperimentalNot described
Receives: Biological: bivalent (RSV/hMPV) unlicensed comparator
VXB-213ExperimentalNot described
Receives: Biological: monovalent (RSV) unlicensed comparator
VXB-221ExperimentalNot described
Receives: Biological: Biological/Vaccine: monovalent (hMPV) unlicensed comparator
VXB-232ExperimentalNot described
Receives: Biological: monovalent (PIV3) unlicensed comparator
PlaceboPlacebo comparatorNot described
Receives: Other: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Proportion of Participants With 1 or More Unsolicited Adverse Events (AEs)

    Measured: 1 month after IMP injection

  2. Proportion of Participants With 1 or More Serious Adverse Events (SAEs), AEs of Special Interest (AESIs), and Premature Discontinuation Associated AEs (PDAEs)

    Measured: 1 month after IMP injection

  3. Proportion of Participants With 1 or More Solicited AEs

    Measured: 7 days after IMP injection

Secondary outcomes (10)

  1. Proportion of Participants With Serious Adverse Events (SAEs), AEs of Special Interest (AESIs), and Premature Discontinuation Associated AEs (PDAEs)

    Measured: 6 and 12 months after IMP injection

  2. Proportion of Participants With 1 or More Severe Solicited AEs

    Measured: 7 days after IMP injection

  3. Geometric Mean Fold Increase (GMFI) of RSV-A, RSV-B, hMPV-A, hMPV-B, and PIV3 Serum Neutralizing Antibody Titers

    GMFI is defined as geometric mean of ratios of specific antibody titer/concentration at each post-injection time point over pre-injection baseline.

    Measured: Pre-injection baseline to 1 month, 6 months, and 12 months, after IMP injection

  4. Geometric Mean Titers (GMTs) of RSV-A, RSV-B, hMPV-A, hMPV-B, and PIV3 Serum Neutralizing Antibody Titers

    Measured: Pre-injection baseline to 1 month, 6 months, and 12 months after IMP injection

  5. Proportion of Participants with Sero-response Greater Than or Equal to (>=) 4-fold (SRR-4) and 8-fold (SRR-8) Increase from Baseline in Neutralizing Antibody Titers for RSV-A, RSV-B, hMPV-A, hMPV-B, and PIV3

    Measured: Pre-injection baseline up to 1 month, 6 months, and 12 months after IMP injection

  6. GMFI of RSV PreF, hMPV PreF, and PIV3 PreF Serum Immunoglobulins G (IgG) Concentrations

    Measured: Pre-injection baseline to 1 month, 6 months, and 12 months after IMP injection

  7. Geometric Mean Concentrations (GMC) of RSV PreF, hMPV PreF, and PIV3 PreF Serum IgG

    Measured: 1 month, 6 months, and 12 months after IMP injection

  8. Geometric Mean Ratios (GMRs) of Fold Increase of RSV-A and RSV-B Neutralizing Serum Antibody Titers Versus Fold Increase of RSV PreF Serum IgG Concentration

    Measured: Pre-injection baseline to 1 month, 6 months, and 12 months after IMP injection

  9. GMR of Fold Increase of hMPV-A and hMPV-B Neutralizing Serum Antibody Titers Versus Fold Increase of hMPV PreF Serum IgG Concentration

    Measured: Pre-injection baseline to 1 month, 6 months, and 12 months after IMP injection

  10. GMR of Fold Increase of PIV3 Neutralizing Serum Antibody Titers Versus Fold Increase PIV3 PreF Serum IgG Concentration

    Measured: Pre-injection baseline to 1 month, 6 months, and 12 months after IMP injection

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted19 Dec 2025
  2. Study start17 Nov 2025
  3. Primary completion21 Apr 2026
  4. Study completion24 Apr 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Sequential
Model description
Stage 1 is a sequential assignment followed by Stage 2 parallel assignment.
Masking
Double blind
Who is masked
Participant, Investigator
Enrolment
240 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07295028
Sponsor's protocol ID
VXB251-001
Other IDs
VCB23397
Acronym
VXB251-001
Status last verified
May 2026
First submitted
24 Nov 2025
Last updated
20 May 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing trivalent (RSV/hMPV/PIV3) vaccine candidate, bivalent (RSV/hMPV) unlicensed comparator and monovalent (RSV) unlicensed comparator in people with Lower Respiratory Tract Disease and Healthy Participants, run by Sanofi at 6 sites in Australia.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 26 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 20 May 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 6 sites in Australia. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Proportion of Participants With 1 or More Unsolicited Adverse Events (AEs) (time frame: 1 month after IMP injection). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07295028.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 May 2026.

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