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 with the study * Medical, work-related, or family problems as a result of alcohol or illicit drug use in the 12 months prior to study entry * History of severe allergic reaction or anaphylaxis * Absence of spleen * Diagnosis of asthma within the 2 years prior to study entry * HIV-1 infected * Hepatitis C virus infected * Positive for hepatitis B surface antigen (HBsAg) * Abnormal blood or urine tests * Known immunodeficiency syndrome * Blood products, including immunoglobulin, within the 3 months prior to study entry * Immune globulin within 3 months of vaccination * Current smoker unwilling to stop smoking for the duration of the study * Participation in another investigational vaccine or drug trial within 30 days of vaccination or while participating in this study * Live vaccine within 4 weeks of vaccination * Killed vaccine within 2 weeks of vaccination * Previous immunization with PIV3 vaccine * Known hypersensitivity to any vaccine component * Other condition that, in the opinion of the investigator, would affect the participant's participation in the study * Work and/or personal responsibilities that involve caring for children less than 6 months of age or immunosuppressed individuals * Pregnancy or breastfeeding Exclusion Criteria for Infant and All Child Participants: * Known or suspected impairment of immune system, including maternal history of positive HIV test, previous receipt of immunosuppressive therapy including systemic corticosteroids, or receipt of bone marrow/solid organ. Participants who have received topical steroids are not excluded. * Major congenital malformations, including congenital cleft palate, cytogenetic abnormalities, or serious chronic disorders * Previous immunization with PIV3 vaccine * Previous serious vaccine-associated adverse event or anaphylactic reaction * Lung or heart disease, including reactive airway disease. Participants with clinically insignificant cardiac abnormalities not requiring treatment are not excluded. More information on this criterion can be found in the protocol. * Clinically significant abnormality in liver function test (seropositive participants only) * Clinically significant abnormality in complete blood count (CBC) (seronegative participants only) * Member of a household that includes a pregnant woman, an immunocompromised individual, or an infant less than 6 months of age * Attends day care with infants less than 6 months of age, pregnant caregivers, or immunosuppressed individuals * Parent or guardian unwilling to suspend day care for 14 days following vaccination. More information on this criterion can be found in the protocol. * Participation in another investigational vaccine or drug trial within 30 days of first vaccination or while participating in this study