Phase 1/2 Study of Respiratory Syncytial Virus and Human Metapneumovirus (RSV+HMPV) Vaccine Candidate in Adults 60 Years of Age and Older

Inclusion Criteria: * Aged 60 years or older on the day of inclusion * Non-childbearing potential (ie, post-menopausal for at least 1 year or surgically sterile) Exclusion Criteria: * History of laboratory-confirmed RSV and/or laboratory-confirmed HMPV infection affecting the participant and/or the participant's household in the previous 12 months * Previous history of myocarditis, pericarditis, and/or myopericarditis * Screening electrocardiogram (ECG) that is consistent with possible myocarditis, pericarditis, and/or myopericarditis or, in the opinion of the investigator, demonstrates clinically relevant abnormalities that may affect participant safety or study results * Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with study conduct or completion * Previous history of Guillain-Barré Syndrome * Any vaccine given 4 weeks before or 4 weeks after study intervention * Previous vaccination against RSV and/or HMPV with an investigational or marketed vaccine * Receipt of any mRNA vaccine/product in the 2 months preceding study intervention administration * Has received a blood transfusion or blood-derived products, including immunoglobulins, in the past 3 months * Any screening laboratory parameter with laboratory abnormality \> Grade 1 or deemed clinically significant by the investigator; if deemed appropriate, investigator may repeat these assessments The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.