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

• 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 COVID-19,
             influenza, rhinovirus, etc.) at the time of enrollment. A prospective participant
             should not be included in the study until the respiratory infection has resolved.
          -  Member of a household that contains an immunocompromised individual, including, but
             not limited to:
               -  a person who is HIV infected
               -  a person who has received chemotherapy within the 12 months prior to study
                  enrollment
               -  a person who has received (within the past 6 months) or is receiving (at the time
                  of enrollment) immunosuppressant agents
               -  a person living with a solid organ or bone marrow transplant
          -  Potential close contact with other immunocompromised individual within 30 days after
             each vaccination as per investigator's discretion
          -  Participant's biological mother's previous receipt or planned administration of an
             investigational RSV vaccine during pregnancy and/or breastfeeding.
          -  Receipt or planned receipt of any of the following vaccines prior to enrollment or
             after the first study intervention administration:
               -  Any other intranasal live attenuated vaccine within the 28 days prior to and
                  after Dose 1 study administration
               -  Unless given on the day of Dose 1 study administration, any other injectable live
                  attenuated vaccines within the 28 days prior to and after. Concomitant receipt on
                  the day of Dose 1 study administration is allowed.
          -  Previous receipt of an investigational RSV vaccine or receiving any anti-RSV product
             (such as ribavirin or RSV immune globulin) at the time of enrollment. Previous receipt
             of an RSV monoclonal antibody within 6 months prior to the first study vaccine
             administration.
          -  Receipt of immune globulins, blood or blood-derived products in the past 3 months
          -  Receipt of intranasal and intra-ocular medications within 3 days prior to study
             enrollment
          -  Participation at the time of study enrollment or planned participation during the
             present study period in another clinical study investigating a vaccine, drug, medical
             device, or medical procedure The above information is not intended to contain all
             considerations relevant to a patient's potential participation in a clinical trial.