Safety of and Immune Response to a Cow/Human Parainfluenza Virus Vaccine (rB/HPIV3) in Healthy Infants, Children, and Adults

Inclusion Criteria for Adult Participants: * Good general health * Available for the duration of the trial * Reachable by telephone for post-vaccination contact * Female participants willing to use acceptable methods of contraception Inclusion Criteria for Seropositive Child Participants: * Good general health and age-appropriate development, as determined by physical exam and medical history review * Seropositive for human parainfluenza type 3 virus (HPIV3), as defined by a serum hemagglutination-inhibition (HI) antibody titer of more than 1:8 * Available for the duration of the trial * Parent or guardian willing to provide informed consent * Parent or guardian reachable by telephone for post-vaccination contact Inclusion Criteria for Seronegative Infant and Child Participants: * Good general health and age-appropriate development, as determined by physical exam and medical history review * Seronegative for HPIV3, as defined by serum HI antibody titer of 1:8 or less within 28 days of first vaccination * Available for the duration of the trial * Parent or guardian willing to provide informed consent * Parent or guardian reachable by telephone for post-vaccination contact Exclusion Criteria for Adult Participants: * Clinically significant neurologic, heart, lung, liver, rheumatologic, autoimmune, or kidney disease * Behavioral, cognitive, or psychiatric disease that, in the opinion of the investigator, affects the ability of the participant to understand and cooperate w…