Recruiting
Phase 1
Phase 2

H5N8 Vaccine

Sponsor:

Sanofi

Code:

NCT07779408

Conditions

Healthy Volunteers

Influenza

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

Interventions

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

Study Details

Brief 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. 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

Study ID

NCT07779408

Start date

Aug 3, 2026

Status verified date

Sep, 2026

Completion date

Feb 22, 2028

Anticipated

Primary completion date

Feb 22, 2028

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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
  • 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.

Study Design

Enrollment

640 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

experimental: Group 1: Flu H5 egg pandemic low dose vaccine, with adjuvant

Participants receive 2 intramuscular injections of flu H5 egg pandemic low dose vaccine, with adjuvant

experimental: Group 2: Flu H5 Egg Pandemic medium dose vaccine, with adjuvant

Participants receive 2 intramuscular injections of flu H5 egg pandemic medium dose vaccine, with adjuvant

experimental: Group 3: Flu H5 Egg Pandemic high dose vaccine, with adjuvant

Participants receive 2 intramuscular injections of flu H5 egg pandemic high dose vaccine, with adjuvant

experimental: Group 4: Flu H5 Egg Pandemic high dose vaccine, without adjuvant

Participants receive 2 intramuscular injections of flu H5 egg pandemic high dose vaccine, without adjuvant

Interventions

Flu H5 egg pandemic low dose vaccine, with adjuvant

Pharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM)

Flu H5 Egg Pandemic medium dose vaccine, with adjuvant

Pharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM)

Flu H5 Egg Pandemic high dose vaccine, with adjuvant

Pharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM)

Flu H5 Egg Pandemic high dose vaccine, without adjuvant

Pharmaceutical form: Suspension for injection Route of administration: Intramuscular (IM)

Primary outcome measure

  • Number of participants with immediate Adverse Events (AEs) [ Time Frame: 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]) [ Time Frame: 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) [ Time Frame: Within 8 days of each vaccination, including the day of vaccination ]
  • 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 ]
  • Number of participants experiencing Medically Attended Adverse Events (MAAEs) [ Time Frame: From Day 01 until the end of the study, approximately 14 months ]
  • Number of participants experiencing Adverse Events of Special Interest (AESIs) [ Time Frame: From Day 01 until the end of the study, approximately 14 months ]
  • Number of participants experiencing Serious Adverse Events (SAEs) [ Time Frame: 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) [ Time Frame: Up to 8 days after each vaccination ]
  • Number of participants experiencing AEs leading to discontinuation [ Time Frame: From Day 01 until the end of the study, approximately 14 months ]
  • Geometric mean titer of hemagglutination inhibition (HAI) assay antibody (Ab) titer [ Time Frame: Day 01 and Day 43 ]
  • Number of participants with HAI Ab titer ≥ 40 (1 dilution [dil]; ie, seroprotection) [ Time Frame: Day 43 ]
  • Number of participants with seroconversion [ Time Frame: Day 01 and Day 43 ]
  • Geometric mean titer ratio of individual HAI Ab titer ratio Day 43/Day 01 [ Time Frame: Day 01 and Day 43 ]

Central Contacts and Locations

Central contacts

Trial Transparency email recommended (Toll free for US & Canada)

800-633-1610Contact-US@sanofi.com

Locations

AMR Clinical Phoenix, Arizona- Site Number : 8400004

Recruiting

Tempe, Arizona, United States, 85281

Peninsula Research Associates- Site Number : 8400011

Recruiting

Rolling Hills Estates, California, United States, 90274

California Research Foundation- Site Number : 8400007

Recruiting

San Diego, California, United States, 92123

Alliance for Multispeciality Research - Coral Gables- Site Number : 8400003

Recruiting

Coral Gables, Florida, United States, 33134

Accel Research Sites Network - DeLand Clinical Research Unit- Site Number : 8400017

Recruiting

DeLand, Florida, United States, 32720

Alliance for Multispeciality Research - Fort Myers- Site Number : 8400001

Recruiting

Fort Myers, Florida, United States, 33912

Indago Research & Health Center- Site Number : 8400010

Recruiting

Miami Lakes, Florida, United States, 33016

Accel Research Sites - NeuroStudies- Site Number : 8400014

Recruiting

Decatur, Georgia, United States, 30030

iResearch Atlanta- Site Number : 8400008

Recruiting

Decatur, Georgia, United States, 30030

AMR Chicago- Site Number : 8400005

Recruiting

Oak Brook, Illinois, United States, 60523

AMR Clinical Newton, Kansas- Site Number : 8400006

Recruiting

Newton, Kansas, United States, 67114

Rochester Clinical Research- Site Number : 8400012

Recruiting

Rochester, New York, United States, 14609

Coastal Carolina Research Center - North Charleston- Site Number : 8400018

Recruiting

North Charleston, South Carolina, United States, 29405

Alliance for Multispecialty Research - Weisgarber Medical Park- Site Number : 8400002

Recruiting

Knoxville, Tennessee, United States, 37909

CenExel JRB - Salth Lake City- Site Number : 8400009

Recruiting

Salt Lake City, Utah, United States, 84107

Charlottesville Medical Research- Site Number : 8400016

Recruiting

Charlottesville, Virginia, United States, 22911

More Information

Sponsor

Sanofi

Last update posted

Sep 15, 2026

Last verified

Sep, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-16. This information was provided to ClinicalTrials.gov by Sanofi on 2026-09-15.