Study to Evaluate Safety and Immunogenicity of a Pandemic Flu H5 mRNA Vaccine in Healthy Adults Aged 18 Years and Older

Inclusion Criteria: * Aged 18 years or older on the day of inclusion. * A female participant is eligible to participate if she is not pregnant or breastfeeding and one of the following conditions applies: * Is of non-childbearing potential. To be considered of non-childbearing potential, a female must be postmenopausal for at least 1 year, or surgically sterile. OR • Is of childbearing potential and agrees to use an effective contraceptive method or abstinence from at least 4 weeks prior to each study intervention administration until at least 12 weeks after the last study intervention administration. * A female participant of childbearing potential must have a negative highly sensitive pregnancy test (urine or serum as required by local regulation) within 8 hours before the first dose of study intervention. Exclusion Criteria: * Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months). * Known systemic hypersensitivity to any of the study intervention components (eg, polyethylene glycol, polysorbate); history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances; any allergic reaction (eg, anaphylaxis) after administration of an mRNA v…