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.

Study of an Investigational H5N8 Influenza Vaccine in Healthy Adults

Age
18 years or above
Gender
All
Phase
Phase 1/2
Participants needed
640
Locations
16
Find a study site near you

Study Overview

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).

Eligibility Criteria

You may be eligible for this study if you meet the following criteria:

  • Conditions: Healthy Volunteers, Influenza
  • Age: 18 years or above
  • Gender: All

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.

The purpose of this research study is to learn about the safety and immune response of an investigational vaccine to help protect against H5N8 influenza in healthy adults ages 18 and older. The study will also compare the vaccine with and without an added ingredient (an adjuvant) to see if the adjuvant improves the vaccine’s effects.

Participants will receive two injections in the arm. They will receive either the investigational H5N8 influenza vaccine at one of three dose levels (low, medium, or high) with the adjuvant, or the investigational vaccine without the adjuvant (high dose).

Who can participate:
Healthy adults 18 years and older may be able to participate if they:

  • Are healthy based on a medical evaluation and medical history
  • Have not had an H5 influenza infection before
  • Have not previously received an influenza vaccine against A(H5) types (including H5N1, H5N8, or H5N6)
  • Do not have a known or suspected immune system problem or recent immune-suppressing treatments
  • Do not have a history (personal or family) of certain nervous system conditions, including Guillain-Barré syndrome
  • Have not received a blood transfusion or blood-derived products (including immunoglobulins) in the past three months
  • Have not received any vaccine in the four weeks before the first study injection and do not plan to receive a vaccine before about three weeks after the second injection

Study timeline and visits:
Participation lasts about 14 months.

Updated on 11 Sep 2026. Study ID: NCT07779408

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