Study of Motavizumab (MEDI-524) and Palivizumab Administered Sequentially in the Same Respiratory Syncytial Virus (RSV) Season

Inclusion Criteria: * The child must have been born at less than or equal to 35 weeks gestation and be less than or equal to 6 months of age at the time of entry into the study (child must be entered on or before his/her 6-month birthday); or the child must be less than or equal to 24 months of age at the time of entry into the study (child must be entered on or before his/her 24-month birthday) and diagnosed with chronic lung disease (CLD) of prematurity with stable or decreasing doses of diuretics, steroids, or bronchodilators, or treatment with supplemental oxygen, within the previous 6 months. * The child must be in general good health at the time of study entry. * The child's parent(s)/legal guardian must provide written informed consent. * The child must be able to complete the follow-up visits through 120-150 days from last injection of study drug. * Parent(s)/legal guardian of patient must have available telephone access. Exclusion Criteria: * Hospitalized at the time of study entry (unless discharge is expected within 10 days after entry into the study) * Receiving chronic oxygen therapy or mechanical ventilation at the time of study entry (including continuous positive airway pressure \[CPAP\]) * Congenital heart disease (CHD) (children with medically or surgically corrected \[closed\] patent ductus arteriosus and no other CHD may be enrolled) * Evidence of infection with hepatitis A, B, or C virus * Known renal impairment, hepatic dysfunction, chronic seizure disorder, or immunodeficiency or HIV infection (a child of a mother with known HIV infection must be proven to be uninfected at the time of enrollment) * Suspected serious allergic or immune-mediated events with prior receipt of palivizumab * Acute illness or progressive clinical disorder * Active infection, including acute RSV infection, at the time of enrollment * Previous reaction to intravenous immunoglobulin (IGIV), blood products, or other foreign proteins * Received within the past 120 days or currently receiving immunoglobulin products (such as RSV-IGIV \[RespiGam\], IVIG, or palivizumab) or any investigational agents * Previous participation in a clinical trial of motavizumab * Currently participating in any investigational study