Healthy VolunteersPhase 1/2NCT07779408
Study to Assess Safety and Immunogenicity of an Egg-based H5N8 Influenza Vaccine at Multiple Dose Levels Adjuvanted With Matrix-M in Healthy Participants 18 Years of Age and Above.
A Phase 1/2 study testing Flu H5 egg pandemic low dose vaccine, with adjuvant, Flu H5 Egg Pandemic medium dose vaccine, with adjuvant and Flu H5 Egg Pandemic high dose vaccine, with adjuvant in people with Healthy Volunteers and Influenza, run by Sanofi at 16 sites in United States.
Trial summary
The study aims to evaluate an egg-based H5N8 influenza vaccine up to 3 dose levels (low, medium, and high dose) given with or without adjuvant to see if the adjuvant improves vaccine effectiveness. The study will enroll healthy adults aged 18 years and over. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Healthy Volunteers, Influenza
- What is being tested?
- Flu H5 egg pandemic low dose vaccine, with adjuvant, Flu H5 Egg Pandemic medium dose vaccine, with adjuvant and Flu H5 Egg Pandemic high dose vaccine, with adjuvant
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 640 participants
- Where
- 16 sitesUnited States
- Study dates
- 3 Aug 2026to 22 Feb 2028
- Phase
- Phase 1/2
- 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 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Aged 18 years or above on the day of inclusion
- Participants who are healthy as determined by medical evaluation including medical history
- Not pregnant/breastfeeding; non-childbearing potential or uses effective contraception/abstinence from ≥4 weeks before the first study intervention dose to ≥8 weeks after the last dose
- Informed consent form has been signed and dated
- Able to attend all scheduled visits and to comply with all study procedures
- Covered by health insurance, if required by local regulations
Who cannot join
- Known or suspected immunodeficiency; immunosuppressive therapy in past 6 months; or long-term systemic corticosteroid (eg, prednisone for more than 2 weeks in the past 3 months)
- Known hepatitis B or hepatitis C infection (based on medical history)
- Known personal or family history of previous episodes of Guillan-Barré syndrome (GBS), neuritis (including Bell's palsy), convulsions, encephalitis, transverse myelitis, and vasculitis
- Known systemic hypersensitivity to any of the study intervention components or history of life-threatening reaction to the study interventions or products with same substances
- Self-reported thrombocytopenia contraindicating intramuscular (IM) injection based on investigator's judgment
- Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating IM injection based on investigator's judgment
Show all 18Show fewer
- Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with study conduct or completion
- History of A/H5 infection prior to the study participation
- Moderate or severe acute illness/infection (per investigator judgment)/fever (≥ 38.0°C [≥ 100.4°F]) on study intervention day. Include participant only after the condition or fever has resolved
- Alcohol, prescription drug, or substance abuse that, in the opinion of the investigator, might interfere with the study conduct or completion
- Any vaccine given 4 weeks before first study intervention or any planned vaccination to be given prior to Day 43 (ie, approximately 21 days after the second study intervention)
- Previous vaccination against A(H5) with an investigational or marketed vaccine. This includes, but is not limited to, influenza subtypes A(H5N1), A(H5N8), and A(H5N6)
- Has received a blood transfusion or blood-derived products, including immunoglobulins in the past 3 months
- Participation in another clinical study for a vaccine, drug, medical device, or medical procedure within 4 weeks before enrollment or planned participation during the present study period
- Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
- Is an investigator, investigator/study center employee, or immediate family member (parent, spouse, natural/adopted child) of the investigator/employee with direct involvement in the study
- Any screening safety laboratory parameters out of normal ranges and assessed as > Grade 2
- The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.
Trial locations and contacts
16 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Trial Transparency email recommended (Toll free for US & Canada) contact
16 sites in 1 country
United States16 sites, 16 recruiting
- Recruiting
Charlottesville Medical Research- Site Number : 8400016
Charlottesville, Virginia, 22911
- Recruiting
Alliance for Multispeciality Research - Coral Gables- Site Number : 8400003
Coral Gables, Florida, 33134
- Recruiting
Accel Research Sites - NeuroStudies- Site Number : 8400014
Decatur, Georgia, 30030
- Recruiting
iResearch Atlanta- Site Number : 8400008
Decatur, Georgia, 30030
- Recruiting
Accel Research Sites Network - DeLand Clinical Research Unit- Site Number : 8400017
DeLand, Florida, 32720
- Recruiting
Alliance for Multispeciality Research - Fort Myers- Site Number : 8400001
Fort Myers, Florida, 33912
- Recruiting
Alliance for Multispecialty Research - Weisgarber Medical Park- Site Number : 8400002
Knoxville, Tennessee, 37909
- Recruiting
Indago Research & Health Center- Site Number : 8400010
Miami Lakes, Florida, 33016
- Recruiting
AMR Clinical Newton, Kansas- Site Number : 8400006
Newton, Kansas, 67114
- Recruiting
Coastal Carolina Research Center - North Charleston- Site Number : 8400018
North Charleston, South Carolina, 29405
- Recruiting
AMR Chicago- Site Number : 8400005
Oak Brook, Illinois, 60523
- Recruiting
Rochester Clinical Research- Site Number : 8400012
Rochester, New York, 14609
- Recruiting
Peninsula Research Associates- Site Number : 8400011
Rolling Hills Estates, California, 90274
- Recruiting
CenExel JRB - Salth Lake City- Site Number : 8400009
Salt Lake City, Utah, 84107
- Recruiting
California Research Foundation- Site Number : 8400007
San Diego, California, 92123
- Recruiting
AMR Clinical Phoenix, Arizona- Site Number : 8400004
Tempe, Arizona, 85281
About this study
Official title: A Phase 1/2, Parallel, Observer-blind Study to Assess the Safety and Immunogenicity of an Egg-based H5N8 Influenza Vaccine at Multiple Dose Levels Adjuvanted With Matrix-M in Healthy Participants 18 Years of Age and Above.
The study aims to evaluate an egg-based H5N8 influenza vaccine up to 3 dose levels (low, medium, and high dose) given with or without adjuvant to see if the adjuvant improves vaccine effectiveness.
The study will enroll healthy adults aged 18 years and over. Participants will receive 2 injections in their arm of either one of the 3 dose levels of the study vaccine (low, medium, or high dose) with the adjuvant or the unadjuvanted vaccine (high dose).
Study duration per participant: approximately 14 months (including screening visit).
- Conditions
- Healthy Volunteers, Influenza
- Being tested
- Flu H5 egg pandemic low dose vaccine, with adjuvant, Flu H5 Egg Pandemic medium dose vaccine, with adjuvant, Flu H5 Egg Pandemic high dose vaccine, with adjuvant, Flu H5 Egg Pandemic high dose vaccine, without adjuvant
- Medical subject headings
- Influenza, Human
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Flu H5 egg pandemic low dose vaccine, with adjuvantBiological
Pharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM)
Flu H5 Egg Pandemic medium dose vaccine, with adjuvantBiological
Pharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM)
Flu H5 Egg Pandemic high dose vaccine, with adjuvantBiological
Pharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM)
Flu H5 Egg Pandemic high dose vaccine, without adjuvantBiological
Pharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM)
| Study group | Role | What they receive |
|---|---|---|
| Group 1: Flu H5 egg pandemic low dose vaccine, with adjuvant | Experimental | Participants receive 2 intramuscular injections of flu H5 egg pandemic low dose vaccine, with adjuvant Receives: Biological: Flu H5 egg pandemic low dose vaccine, with adjuvant |
| Group 2: Flu H5 Egg Pandemic medium dose vaccine, with adjuvant | Experimental | Participants receive 2 intramuscular injections of flu H5 egg pandemic medium dose vaccine, with adjuvant Receives: Biological: Flu H5 Egg Pandemic medium dose vaccine, with adjuvant |
| Group 3: Flu H5 Egg Pandemic high dose vaccine, with adjuvant | Experimental | Participants receive 2 intramuscular injections of flu H5 egg pandemic high dose vaccine, with adjuvant Receives: Biological: Flu H5 Egg Pandemic high dose vaccine, with adjuvant |
| Group 4: Flu H5 Egg Pandemic high dose vaccine, without adjuvant | Experimental | Participants receive 2 intramuscular injections of flu H5 egg pandemic high dose vaccine, without adjuvant Receives: Biological: Flu H5 Egg Pandemic high dose vaccine, without adjuvant |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of participants with immediate Adverse Events (AEs)
Immediate adverse events are medically relevant unsolicited systemic adverse events reported in the 30 minutes after vaccination
Measured: Within 30 minutes after each vaccination
Number of participants experiencing solicited administration site reactions (pre-listed in the participant diary and case report form [CRF])
A solicited reaction is an adverse reaction (sign or symptom) observed and reported under the conditions pre-listed (for example: injection site pain or headache). Solicited administration site reactions are reactions at and around the injection/administration site
Measured: Within 8 days of each vaccination, including the day of vaccination
Number of participants experiencing solicited systemic reactions (pre-listed in the participant diary and CRF)
All solicited reactions that are not solicited injection or administration site reactions
Measured: Within 8 days of each vaccination, including the day of vaccination
Number of participants experiencing unsolicited AEs
Unsolicited AE: an observed AE that does not fulfill the conditions of solicited reactions
Measured: Within 21 days after the first vaccination, including the day of the first vaccination, and within 28 days after the second vaccination, including the day of the second vaccination
Number of participants experiencing Medically Attended Adverse Events (MAAEs)
MAAEs are collected throughout the study
Measured: From Day 01 until the end of the study, approximately 14 months
Number of participants experiencing Adverse Events of Special Interest (AESIs)
AESIs are collected throughout the study
Measured: From Day 01 until the end of the study, approximately 14 months
Number of participants experiencing Serious Adverse Events (SAEs)
SAEs are collected throughout the study
Measured: From Day 01 until the end of the study, approximately 14 months
Number of participants experiencing out-of-range biological test results (including shift from baseline values)
Safety laboratory assessments will include clinical chemistry and hematology
Measured: Up to 8 days after each vaccination
Number of participants experiencing AEs leading to discontinuation
AEs leading to discontinuation are collected throughout the study
Measured: From Day 01 until the end of the study, approximately 14 months
Geometric mean titer of hemagglutination inhibition (HAI) assay antibody (Ab) titer
Influenza vaccine antibody titers are measured by HAI assay
Measured: Day 01 and Day 43
Number of participants with HAI Ab titer ≥ 40 (1 dilution [dil]; ie, seroprotection)
Influenza vaccine antibody titers are measured by HAI assay
Measured: Day 43
Number of participants with seroconversion
Seroconversion is defined as HAI Ab titer < 10 (1/dil) on Day 01 and post-injection titer ≥ 40 (1/dil) on Day 43; or defined as HAI Ab titer ≥ 10 (1/dil) on Day 01 and a ≥ 4-fold increase in titer (1/dil) on Day 43
Measured: Day 01 and Day 43
Geometric mean titer ratio of individual HAI Ab titer ratio Day 43/Day 01
Influenza vaccine antibody titers are measured by HAI assay
Measured: Day 01 and Day 43
Secondary outcomes (12)
Geometric mean titer of hemagglutination inhibition (HAI) assay antibody (Ab) titer obtained on Day 01, Day 22, Day 43, Day 202
Influenza vaccine antibody titers are measured by HAI assay
Measured: Day 01, Day 22, Day 43, Day 202
Geometric mean titer ratio of individual HAI Ab titer ratios Day 22/Day 01, Day 43/Day 01, Day 202/Day 43
Individual HAI Ab titer ratios are calculated for the following time points: Day 22/Day 01, Day 43/Day 01 and Day 202/Day 43
Measured: Day 01, Day 22, Day 43, Day 202
Number of participants with individual HAI Ab titer ≥ 40 (1/dil) on Day 01, Day 22, Day 43, Day 202
Influenza vaccine antibody titers are measured by HAI assay
Measured: Day 01, Day 22, Day 43, Day 202
Number of participants with seroconversion on Day 22 compared to Day 01 (baseline)
Seroconversion is defined as titer < 10 (1/dil) on Day 01 and post-injection titer ≥ 40 (1/dil) on Day 22; or defined as titer ≥ 10 (1/dil) on Day 01 and a ≥ 4 fold increase in titer (1/dil) on Day 22
Measured: Day 01, Day 22
Number of participants with detectable HAI Ab titer
Detectable HAI Ab titer: a titer ≥ 10 (1/dil)
Measured: Day 01, Day 22, Day 43, Day 202
Geometric mean titer of neutralization (NT) Ab titer
Influenza vaccine antibody titers are measured by serum neutralization (SN) assay
Measured: Day 01, Day 22, Day 43, Day 202
Geometric mean titer ratio of individual NT Ab titer ratio
Individual NT Ab titer ratios are calculated for the following time points: Day 22/Day 01, Day 43/Day 01 and Day 202/Day 43
Measured: Day 01, Day 22, Day 43, Day 202
Number of participants with NT Ab titer ≥ 20 (1/dil)
NT Ab titer ≥ 20 (1/dil) on Day 43; compared to Day 01 and Day 202
Measured: Day 01, Day 43, Day 202
Number of participants with NT Ab titer ≥ 40 (1/dil)
NT Ab titer ≥ 40 (1/dil) on Day 43; compared to Day 01 and Day 202
Measured: Day 01, Day 43, Day 202
Number of participants with NT Ab titer ≥ 80 (1/dil)
NT Ab titer ≥ 80 (1/dil) on Day 43; compared to Day 01 and Day 202
Measured: Day 01, Day 43, Day 202
Geometric mean fold-rise of fold increase in NT Ab titer [post/pre] ≥ 2 and ≥ 4
Influenza vaccine antibody titers are measured by serum neutralization (SN) assay
Measured: Day 43
Number of participants with detectable NT Ab titer
Detectable NT Ab titer: a titer ≥ 10 (1/dil) on Day 01, Day 22, Day 43, Day 202
Measured: Day 01, Day 22, Day 43, Day 202
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Aug 2026
- Study start3 Aug 2026
- Primary completion22 Feb 2028 (estimated)
- Study completion22 Feb 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy VolunteersStudies of the same condition, open and under way.
- More trials run by SanofiThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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 1/2
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Parallel, multi-center, controlled study.
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 640 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Sanofi
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07779408
- Sponsor's protocol ID
- VBX21138
- Other IDs
- U1111-1325-2670
- Status last verified
- Sep 2026
- First submitted
- 31 Jul 2026
- Last updated
- 15 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: 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
Study at a glance
From the registry record, last updated by the sponsor on 15 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1/2, Parallel, Observer-blind Study to Assess the Safety and Immunogenicity of an Egg-based H5N8 Influenza Vaccine at Multiple Dose Levels Adjuvanted With Matrix-M in Healthy Participants 18 Years of Age and Above.
- ClinicalTrials.gov ID
- NCT07779408
- Acronym / sponsor ID
- VBX21138
- Conditions
- Healthy Volunteers, Influenza
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 640 participants (estimated)
- Lead sponsor
- SanofiIndustry (pharma, biotech, devices)
- Study start
- 3 Aug 2026 (actual)
- Primary completion
- 22 Feb 2028 (estimated)
- Study completion
- 22 Feb 2028 (estimated)
- First posted
- 21 Aug 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The study aims to evaluate an egg-based H5N8 influenza vaccine up to 3 dose levels (low, medium, and high dose) given with or without adjuvant to see if the adjuvant improves vaccine effectiveness.
The study will enroll healthy adults aged 18 years and over. Participants will receive 2 injections in their arm of either one of the 3 dose levels of the study vaccine (low, medium, or high dose) with the adjuvant or the unadjuvanted vaccine (high dose).
Study duration per participant: approximately 14 months (including screening visit).
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 4
- Model description
- Parallel, multi-center, controlled study.
| Arm | Type | Receives |
|---|---|---|
| Group 1: Flu H5 egg pandemic low dose vaccine, with adjuvant | Experimental | Biological: Flu H5 egg pandemic low dose vaccine, with adjuvantParticipants receive 2 intramuscular injections of flu H5 egg pandemic low dose vaccine, with adjuvant |
| Group 2: Flu H5 Egg Pandemic medium dose vaccine, with adjuvant | Experimental | Biological: Flu H5 Egg Pandemic medium dose vaccine, with adjuvantParticipants receive 2 intramuscular injections of flu H5 egg pandemic medium dose vaccine, with adjuvant |
| Group 3: Flu H5 Egg Pandemic high dose vaccine, with adjuvant | Experimental | Biological: Flu H5 Egg Pandemic high dose vaccine, with adjuvantParticipants receive 2 intramuscular injections of flu H5 egg pandemic high dose vaccine, with adjuvant |
| Group 4: Flu H5 Egg Pandemic high dose vaccine, without adjuvant | Experimental | Biological: Flu H5 Egg Pandemic high dose vaccine, without adjuvantParticipants receive 2 intramuscular injections of flu H5 egg pandemic high dose vaccine, without adjuvant |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Aged 18 years or above on the day of inclusion
- Participants who are healthy as determined by medical evaluation including medical history
- Not pregnant/breastfeeding; non-childbearing potential or uses effective contraception/abstinence from ≥4 weeks before the first study intervention dose to ≥8 weeks after the last dose
- Informed consent form has been signed and dated
- Able to attend all scheduled visits and to comply with all study procedures
Key exclusion criteria (18 listed)
- Known or suspected immunodeficiency; immunosuppressive therapy in past 6 months; or long-term systemic corticosteroid (eg, prednisone for more than 2 weeks in the past 3 months)
- Known hepatitis B or hepatitis C infection (based on medical history)
- Known personal or family history of previous episodes of Guillan-Barré syndrome (GBS), neuritis (including Bell's palsy), convulsions, encephalitis, transverse myelitis, and vasculitis
- Known systemic hypersensitivity to any of the study intervention components or history of life-threatening reaction to the study interventions or products with same substances
- Self-reported thrombocytopenia contraindicating intramuscular (IM) injection based on investigator's judgment
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Flu H5 egg pandemic low dose vaccine, with adjuvantPharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM) | Biological | Group 1: Flu H5 egg pandemic low dose vaccine, with adjuvant |
| Flu H5 Egg Pandemic medium dose vaccine, with adjuvantPharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM) | Biological | Group 2: Flu H5 Egg Pandemic medium dose vaccine, with adjuvant |
| Flu H5 Egg Pandemic high dose vaccine, with adjuvantPharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM) | Biological | Group 3: Flu H5 Egg Pandemic high dose vaccine, with adjuvant |
| Flu H5 Egg Pandemic high dose vaccine, without adjuvantPharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM) | Biological | Group 4: Flu H5 Egg Pandemic high dose vaccine, without adjuvant |
Primary outcome
Number of participants with immediate Adverse Events (AEs)
Time frame: Within 30 minutes after each vaccination
Immediate adverse events are medically relevant unsolicited systemic adverse events reported in the 30 minutes after vaccination
Number of participants experiencing solicited administration site reactions (pre-listed in the participant diary and case report form [CRF])
Time frame: Within 8 days of each vaccination, including the day of vaccination
A solicited reaction is an adverse reaction (sign or symptom) observed and reported under the conditions pre-listed (for example: injection site pain or headache). Solicited administration site reactions are reactions at and around the injection/administration site
Number of participants experiencing solicited systemic reactions (pre-listed in the participant diary and CRF)
Time frame: Within 8 days of each vaccination, including the day of vaccination
All solicited reactions that are not solicited injection or administration site reactions
Number of participants experiencing unsolicited AEs
Time frame: Within 21 days after the first vaccination, including the day of the first vaccination, and within 28 days after the second vaccination, including the day of the second vaccination
Unsolicited AE: an observed AE that does not fulfill the conditions of solicited reactions
Number of participants experiencing Medically Attended Adverse Events (MAAEs)
Time frame: From Day 01 until the end of the study, approximately 14 months
MAAEs are collected throughout the study
Number of participants experiencing Adverse Events of Special Interest (AESIs)
Time frame: From Day 01 until the end of the study, approximately 14 months
AESIs are collected throughout the study
Number of participants experiencing Serious Adverse Events (SAEs)
Time frame: From Day 01 until the end of the study, approximately 14 months
SAEs are collected throughout the study
Number of participants experiencing out-of-range biological test results (including shift from baseline values)
Time frame: Up to 8 days after each vaccination
Safety laboratory assessments will include clinical chemistry and hematology
Number of participants experiencing AEs leading to discontinuation
Time frame: From Day 01 until the end of the study, approximately 14 months
AEs leading to discontinuation are collected throughout the study
Geometric mean titer of hemagglutination inhibition (HAI) assay antibody (Ab) titer
Time frame: Day 01 and Day 43
Influenza vaccine antibody titers are measured by HAI assay
Number of participants with HAI Ab titer ≥ 40 (1 dilution [dil]; ie, seroprotection)
Time frame: Day 43
Influenza vaccine antibody titers are measured by HAI assay
Number of participants with seroconversion
Time frame: Day 01 and Day 43
Seroconversion is defined as HAI Ab titer < 10 (1/dil) on Day 01 and post-injection titer ≥ 40 (1/dil) on Day 43; or defined as HAI Ab titer ≥ 10 (1/dil) on Day 01 and a ≥ 4-fold increase in titer (1/dil) on Day 43
Geometric mean titer ratio of individual HAI Ab titer ratio Day 43/Day 01
Time frame: Day 01 and Day 43
Influenza vaccine antibody titers are measured by HAI assay
12 secondary outcomes
Geometric mean titer of hemagglutination inhibition (HAI) assay antibody (Ab) titer obtained on Day 01, Day 22, Day 43, Day 202
Time frame: Day 01, Day 22, Day 43, Day 202
Geometric mean titer ratio of individual HAI Ab titer ratios Day 22/Day 01, Day 43/Day 01, Day 202/Day 43
Time frame: Day 01, Day 22, Day 43, Day 202
Number of participants with individual HAI Ab titer ≥ 40 (1/dil) on Day 01, Day 22, Day 43, Day 202
Time frame: Day 01, Day 22, Day 43, Day 202
Number of participants with seroconversion on Day 22 compared to Day 01 (baseline)
Time frame: Day 01, Day 22
Number of participants with detectable HAI Ab titer
Time frame: Day 01, Day 22, Day 43, Day 202
Geometric mean titer of neutralization (NT) Ab titer
Time frame: Day 01, Day 22, Day 43, Day 202
Geometric mean titer ratio of individual NT Ab titer ratio
Time frame: Day 01, Day 22, Day 43, Day 202
Number of participants with NT Ab titer ≥ 20 (1/dil)
Time frame: Day 01, Day 43, Day 202
Number of participants with NT Ab titer ≥ 40 (1/dil)
Time frame: Day 01, Day 43, Day 202
Number of participants with NT Ab titer ≥ 80 (1/dil)
Time frame: Day 01, Day 43, Day 202
Geometric mean fold-rise of fold increase in NT Ab titer [post/pre] ≥ 2 and ≥ 4
Time frame: Day 43
Number of participants with detectable NT Ab titer
Time frame: Day 01, Day 22, Day 43, Day 202
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Sep 2026.
- VBX21138 Plain Language Results SummaryLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. 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
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Screening Protocol
Pain
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Trial Transparency email recommended (Toll free for US & Canada) contact
16 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing Flu H5 egg pandemic low dose vaccine, with adjuvant, Flu H5 Egg Pandemic medium dose vaccine, with adjuvant and Flu H5 Egg Pandemic high dose vaccine, with adjuvant in people with Healthy Volunteers and Influenza, run by Sanofi at 16 sites in United States.
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 6 inclusion and 18 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: looking for participants now, as of the sponsor's last update on 15 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 16 sites in United States. 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. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined 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.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
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?
Contact Trial Transparency email recommended (Toll free for US & Canada) (800-633-1610 ext. option 6, Contact-US@sanofi.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of participants with immediate Adverse Events (AEs) (time frame: Within 30 minutes after each vaccination). The study lists 13 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 15 Sep 2026.