Evaluating the Safety and Immune Response to a Respiratory Syncytial Virus (RSV) Vaccine in Adults, RSV-Seropositive Children, and RSV-Seronegative Infants and Children

The purpose of this study is to evaluate the safety and immune response of the RSV MEDI ΔM2-2 vaccine in the four groups of participants. The study vaccine will be evaluated in adults, in RSV-seropositive children, and in a dose-ranging study in two groups of RSV-seronegative infants and children.