Evaluating the Safety and Immunogenicity of a Human Parainfluenza Type 3 (HPIV3) Virus Vaccine in Infants and Children

Inclusion Criteria: * Parent/guardian(s) of participants can demonstrate their understanding of the study (by taking a multiple choice questionnaire), sign the informed consent, and agree to vaccine administration following a detailed explanation of the study * Seronegative for HPIV3, as defined by serum antibody titer hemagglutination inhibition (HAI) less than or equal to 1:8, as determined within 30 days prior to inoculation * Medical history has been reviewed and a physical examination indicates that participant is in good health * In the view of the site investigator, participant has received routine immunizations appropriate for age, administered at least 2 weeks prior to study entry (inactivated and subunit vaccines and rotavirus vaccine), or at least 4 weeks prior to study entry (live vaccines except rotavirus vaccine) * Available for the entire study period and parent/guardian can be reached by telephone for post-inoculation contacts * For children born to HIV-infected women, the child can be considered HIV-uninfected if he/she has either two negative polymerase chain reaction (PCR) tests with one collected at greater than 1 month of age and one collected at greater than 4 months of age, or two negative antibody tests * If there is an immunocompromised child in the household who is less than 5 years of age, his/her last CD4 count must be greater than 15% Exclusion Criteria: * Known or suspected impairment of immunological functions, HIV infection, or currently (wi…