A Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Immunogenicity of a Single Intravenous Dose of MEDI-524, a Humanized Enhanced Potency Monoclonal Antibody to Respiratory Syncytial Virus (RSV), in Otherwise Healthy Children Hospitalized With RSV Infection

• To describe the safety and tolerability of a single intravenous dose of MEDI-524
• To describe the serum concentrations of IV administered MEDI-524

• - To describe the safety and tolerability of a single intravenous dose of MEDI-524 administered at 3 mg/kg, 15 mg/kg, and 30 mg/kg in otherwise healthy infants hospitalized for RSV infection
• - To describe the serum concentrations of IV administered MEDI-524 in these children with RSV infection

MEDI-524 administered as a single IV dose at 3, 15, and 30 mg/kg to children hospitalized with RSV infection was safe and well tolerated.

Inclusion Criteria:

• All male or female children must have met all of the following criteria:
• Previously healthy
• Age £24 months at the time of randomization
• Gestational age ³36 weeks gestation
• Randomization within 24 hours after hospitalization
• Hospitalized for lower respiratory tract illness (i.e. RSV bronchiolitis and/or pneumonia) documented by positive RSV antigen detection or culture in respiratory secretions within 72 hours before randomization

Exclusion Criteria:

• Patients who met any of the following criteria were not eligible for entry into the study:
• Already received or would receive ribavirin or other anti-viral treatment for the current episode of RSV infection prior to randomization
• Required intubation for ventilatory support
• Any medically significant underlying ongoing chronic illness or organ system dysfunction or other known acute illness, other than RSV infection
• Known renal impairment, hepatic dysfunction, hematologic abnormalities, seizure or other neurologic disorder or immunodeficiency
• Requirement for supplemental oxygen at any time prior to the current RSV infection (brief use of oxygen in the immediate postnatal period to treat a transient condition was allowed)
• Mechanical ventilation at any time prior to the onset of the current RSV infection
• Congenital heart disease (children with medically or surgically corrected patent ductus arteriosus [PDA], small atrial septal defect [ASD] or ventricular septal defect [VSD] were allowed)
• Previous reaction to IVIG, blood products, or other foreign proteins
• Prior use of IVIG, RSV-IGIV (RespiGamÒ), palivizumab (SynagisÒ), or other immunoglobulin products within the past 2 months
• Currently receiving other investigational agents or have received any other investigational agents within the last 3 months
• Prior or current participation in any investigational study with a therapeutic agent or vaccine for RSV