Clesrovimab (MK-1654) in Infants and Children at Increased Risk for Severe Respiratory Syncytial Virus (RSV) Disease (MK-1654-007)

Inclusion Criteria: * Participants at increased risk for severe RSV infection recommended to receive palivizumab in accordance with national or local guidelines or professional society recommendations and meet defined criteria for the Early or Moderate Pre-term Group or the chronic lung disease (CLD)/congenital heart disease (CHD) Group. * Is available to complete the follow-up period. Additional inclusion criteria for participation in RSV Season 2: * RSV Season 2 participants enrolled in the CLD/CHD Group in RSV Season 1. Participants with CHD must also have the following: * Hemodynamically significant CHD at the beginning of RSV Season 2, or * If the participant has had surgically repaired hemodynamically significant CHD that did not include extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass: 1) continues to require medications to manage CHD, or 2) any additional medical intervention related to their CHD. * RSV Season 2 participants enrolled in the Early or Moderate Pre-term Group in RSV Season 1, with the following: * Neuromuscular disease or congenital pulmonary anomaly that impairs the ability to clear secretions from the upper airway because of ineffective cough * Down Syndrome (trisomy of chromosome 21) * Cystic fibrosis with nutritional compromise * Native Americans and Alaskan Indians or other indigenous populations at high risk for severe RSV disease Exclusion Criteria: * Requires mechanical ventilation at time of enrollment. * H…