Safety and Immunogenicity of the RSV D46cpΔM2-2 Vaccine in RSV-Seropositive Children and RSV-Seronegative Infants and Children

RSV-Seropositive Children: Inclusion Criteria: * Greater than or equal to 12 months of age and less than 60 months of age * Received routine immunizations appropriate for age * Serum RSV neutralizing antibody titer greater than or equal to 1:40 * Serum RSV neutralizing antibody result obtained this calendar year * Pre-inoculation serum RSV neutralizing antibody specimen obtained less than or equal to 56 days prior to inoculation * Parent/guardian has completed the study comprehension assessment * Parent/guardian has signed the study informed consent document (ICD) * Subject is expected to be available for the duration of the study Exclusion Criteria: * Evidence of chronic disease * Within the past 6 months had a decline in height or weight growth that crosses two major growth percentiles (e.g., from above the 75th to below the 25th) * Known or suspected impairment of immune function * Maternal history of positive HIV test * Bone marrow/solid organ transplant recipient * Major congenital malformations, including congenital cleft palate or cytogenetic abnormalities * Current or unresolved suspected or documented developmental disorder, delay, or other developmental problem * Cardiac abnormality requiring treatment * Lung disease or reactive airway disease * More than one episode of wheezing in the first year of life * Wheezing episode or received bronchodilator therapy within the past 12 months * Previous immunization with an experimental RSV vaccine * Previous receipt or planned administration of anti-RSV antibody product * Previous serious vaccine-associated AE or anaphylactic reaction * Known hypersensitivity to any vaccine component * Previous receipt of immunoglobulin or any antibody products * Previous receipt of any other blood products within the past 6 months * Member of a household that contains an infant who is less than 12 months of age during study days 0 to 10 * Member of a household that includes an immunocompromised individual * Member of a household that includes a person who has received chemotherapy within the past 12 months * Will attend a daycare facility that does not separate children by age and contains an infant who is greater than 12 months of age during study days 0 to 10 RSV-Seronegative Infants and Children: Inclusion Criteria: * Greater than or equal to 6 months of age and less than 25 months of age * Received routine immunizations appropriate for age * Serum RSV neutralizing antibody titer is less than 1:40 * Screening and pre-inoculation serum RSV neutralizing antibody specimen obtained less than or equal to 42 days prior to inoculation * Parent/guardian has completed the study comprehension assessment * Parent/guardian has signed the study ICD * Subject is expected to be available for the duration of the study * Born at greater than or equal to 37 weeks gestation or is currently greater than 1 year of age Exclusion Criteria: * Evidence of chronic disease * Within the past 6 months had a decline in height or weight growth that crosses two major growth percentiles (e.g., from above the 75th to below the 25th) * Known or suspected impairment of immune function * Maternal history of positive HIV test * Bone marrow/solid organ transplant recipient * Major congenital malformations, including congenital cleft palate or cytogenetic abnormalities * Current or unresolved suspected or documented developmental disorder, delay, or other developmental problem * Cardiac abnormality requiring treatment * Lung disease or reactive airway disease * More than one episode of wheezing in the first year of life * Wheezing episode or received bronchodilator therapy within the past 12 months * Previous immunization with an experimental RSV vaccine * Previous receipt or planned administration of anti-RSV antibody product * Previous receipt of immunoglobulin or any antibody products * Previous receipt of any other blood products within the past 6 months * Previous serious vaccine-associated AE or anaphylactic reaction * Known hypersensitivity to any vaccine component * Member of a household which contains an infant who is less than 6 months of age during study days 0 to 28 * Member of a household that includes an immunocompromised individual * Member of a household that includes a person who has received chemotherapy within the past 12 months * Will attend a daycare facility that does not separate children by age and contains an infant who is less than 6 months of age during study days 0 to 28 Temporary Exclusion Criteria for RSV-Seropositive and RSV-Seronegative Children: To be eligible to participate, RSV-seropositive and RSV-seronegative infants and children must satisfy none of the temporary exclusion criteria. The following conditions are temporary or self-limiting. Once the condition is resolved and the subject is otherwise eligible, the subject may be enrolled or rescreened, if necessary. * Any of the following events at the time of inoculation: * fever (rectal temperature of greater than or equal to 100.4°F), * upper respiratory signs or symptoms (rhinorrhea, cough, or pharyngitis) * nasal congestion significant enough to interfere with successful inoculation * otitis media * Receipt of any killed vaccine or live-attenuated rotavirus vaccine less than 14 days prior to inoculation * Receipt of the following medications less than 28 days prior to inoculation: * any live vaccine other than rotavirus * another investigational vaccine or investigational drug, * systemic corticosteroids administered for greater than 14 days at a dosage equivalent to prednisone at greater than 2 mg/kg or 20 mg daily * salicylate (aspirin) or salicylate-containing products * Receipt of a non-permitted concomitant medication or any of the following medications less than 3 days prior to inoculation: * systemic antibacterial, antiviral, antifungal, anti-parasitic, or antituberculous agents, whether for treatment or prophylaxis, * intranasal medications * Scheduled administration of the following in relation to planned inoculation: * killed vaccine within the 14 days following, * any live vaccine other than rotavirus within the 28 days following, * another investigational vaccine or drug within the 28 days following for RSV-seropositive children and the 56 days following for RSV-seronegative infants and children