A Phase 3 Trial of the Effect of Motavizumab Prophylaxis on Reduction of Serious Early Childhood Wheezing in Infants

Inclusion Criteria: * Male or female infants born at 32 \& 1/7 - 35 \& 0/7 weeks GA, determined according to available medical records * Chronological age of \<6 months of age at randomization * In good health, in the opinion of the investigator * Not more than one of the following AAP-defined risk factors: 1. Childcare attendance 2. School-aged siblings 3. Exposure to environmental air pollutants (not including passive exposure to tobacco smoke) * Ability and willingness of the subject's parent/legal guardian to complete all protocol-mandated follow-up telephone contacts, visits and procedures * Written informed consent obtained from the subject's parent(s) or legal guardian Exclusion Criteria: * Diagnosis of CLD of prematurity (also referred to as BPD) or other chronic pulmonary diseases * Diagnosis of hemodynamically significant CHD, defined as requiring medication or supplemental oxygen for their CHD * Congenital abnormalities of the airways * Severe neuromuscular disease, as determined by the investigator * Previous or concurrent treatment with palivizumab or intravenous immunoglobulin (IVIG) * Eligible for prophylaxis based on local medical standards and guidelines at participating sites * Known immunodeficiency * Previous or current diagnosis of an upper or lower respiratory infection by a medical professional * Previous or current diagnosis of wheezing, asthma, or other wheezing-related diagnoses * Hospitalization at the time of enrollment (in case admitted to nursery as part of routine care, infant should only be randomized immediately prior to being discharged) * Any illness or condition that would preclude long-term survival * Participation in a trial or an investigational agent for RSV prophylaxis or therapy * Inability to be followed through their 3rd birthday