Efficacy, Immunogenicity, and Safety Study of a Respiratory Syncytial Virus Vaccine in Infants and Toddlers

Inclusion Criteria: -Aged 6 months to \< 22 months on the day of inclusion (means the day of the 6-month birthday to the day before the 22-month birthday) * Participants who are healthy as determined by medical evaluation including medical history * Born at full term of pregnancy (≥ 37 weeks) 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) * Known systemic hypersensitivity to any of the study intervention components, or history of a life-threatening reaction to the study intervention used in the study or to a product containing any of the same substances * Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with study conduct or completion * History of medically diagnosed wheezing * Any acute febrile illness in the past 48 hours that according to investigator judgment is significant enough to interfere with successful inoculation 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. * Probable or confirmed ongoing case of viral respiratory infection (including C…