Study of Palivizumab in Children With High Risk of Severe Respiratory Syncytial Virus (RSV) Disease

Inclusion Criteria: 1. Participants at risk of severe RSV disease defined as fulfilling at least one of the following: 1. Infants born ≤ 35 wGA and are \< 6 months of age at enrolment. 2. Children \< 24 months of age at enrolment and requiring treatment for BPD within the last 6 months. 3. Children \< 24 months of age and with haemodynamically significant CHD. 2. Written informed consent obtained from the participant's parent(s)/legal guardian and the participant's parent(s)/legal guardian is able to understand and comply with the requirements of the protocol including follow-up visits as judged by the investigator. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: 1. Hospitalisation at the time of enrolment, unless the discharge is expected within 30 days of the time of enrolment 2. Required mechanical ventilation (including continuous positive airway pressure) or other mechanical respiratory or cardiac support at the time of enrolment. 3. Anticipated cardiac surgery within 2 weeks after enrolment. 4. Anticipated survival of \< 6 months after enrolment in the trial. 5. Active LRTD, including RSV infection at the time of enrolment and/or study intervention administration. 6. Any fever (≥ 38.0°C) or acute illness within 7 days prior to investigational product administration. 7. Known history of evolving or unstable neurologic disorder. 8. Known history of unstable cardiac or respiratory status, including cardiac defects so severe that survival is not expected or for which cardiac transplantation is planned or anticipated. 9. Known allergy, including to immunoglobulin products, or history of allergic reaction. 10. Receipt of palivizumab or other RSV monoclonal antibodies or any RSV vaccine, including maternal RSV vaccination. 11. Receipt of any monoclonal or polyclonal antibody (for example, hepatitis B immune globulin, intravenous immunoglobulin) or anticipated use during the study. 12. Concurrent enrolment in another interventional study. 13. Children of employees of the sponsor, clinical study site, or any other individuals involved with the conduct of the study, or immediate family members of such individuals. 14. Judgment by the investigator that the participant should not participate in the study if the participant or the participant's parent/legal guardian is unlikely to comply with study procedures, restrictions, and requirements.