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.

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.