Safety and Immunogenicity of Quadrivalent Influenza mRNA Vaccine MRT5407 in Adult Participants18 Years of Age and Older

Inclusion Criteria: * Aged 18 years 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 study intervention administration until at least 12 weeks after study intervention administration. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: * 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) * Previous history of myocarditis, pericarditis, and / or myopericarditis * Self-reported thrombocytopenia, contraindicating Intramuscular vaccination based on Investigator's judgment * Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating Intramuscular vaccination based on Investigator's judgment * Moderate or severe acute illness / infection (according to Investigator's judgment) or febrile illness (temperature ≥ 38.0°C \[≥ 100.4°F\]) on the day of vaccination. A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided * Self-reported or documented seropositivity for human immunodeficiency virus, hepatitis B virus, or hepatitis C virus * Receipt of any mRNA vaccine/product in the 2 months preceding study intervention administration NOTE: The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.