Safety of a Live Attenuated Human Parainfluenza Virus Type 2 (HPIV2) Vaccine for Adults, Children, and Infants

Inclusion Criteria for Adults: * 18 to 49 years old * In good health, measured by lack of significant medical illness, physical examination findings, or significant laboratory abnormalities of urinalysis, complete blood count (CBC), ALT, or creatinine, as determined by the investigator Exclusion Criteria for Adults: * Pregnancy * Breastfeeding * Females of childbearing potential who are unwilling to practice effective birth control * Evidence of clinically significant neurologic, cardiac, pulmonary, hepatic, rheumatologic, autoimmune, or renal disease by history, physical examination, or laboratory studies, including urinalysis * 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 protocol * Other condition that, in the opinion of the investigator, would jeopardize the safety or rights of a participant participating in the study or would render the participant unable to comply with the protocol * Has had medical, occupational, or family problems as a result of alcohol or illicit drug use during the past 12 months * History of a severe allergic reaction or anaphylaxis * History of splenectomy * Diagnosis of asthma within the past 2 years * Positive enzyme-linked immunoassay (ELISA) and confirmatory Western blot tests for HIV-1 * Positive ELISA and confirmatory immunoblot tests for hepatitis C virus (HCV) * Positive ELISA hepatitis B surface antigen (HBsAg) test * Abnormal urinalysis or urine dip * Known immunodeficiency syndrome * Current use of nasal or systemic steroid medications * Receipt of blood products (including immunoglobulin) within the past 3 months * Current smoker unwilling to stop smoking for the duration of the study * Participation in another investigational vaccine or drug study within 30 days of receiving the investigational vaccine * Receipt of a live vaccine within the past 4 weeks or a killed vaccine within the past 2 weeks or immune globulin within the last 3 months prior to receiving the investigational vaccine * Previous immunization with an HPIV2 vaccine * Known hypersensitivity to any vaccine component * Professional or personal responsibilities involve caring for children less than 59 months of age or for immunosuppressed individuals * Systolic blood pressure greater than 140 mm Hg or diastolic blood pressure greater than 90 mm Hg * Body mass Index (BMI) greater than 35 Inclusion Criteria for Seropositive Children: * Children 15 to 59 months of age * Parent or guardian understands and signs the informed consent * Seropositive for HPIV2, as defined by serum hemagglutinin inhibition (HAI) antibody titer in ratio greater than 1:8 * History has been reviewed and participant has undergone a physical examination indicating good health * Participant is expected to be available for the duration of the study Exclusion Criteria for Seropositive Children: * Known or suspected impairment of immunological functions, including maternal history of positive HIV test, receiving immunosuppressive therapy, including systemic corticosteroids or bone marrow/solid organ transplant recipients (topical steroids, topical antibiotics, and topical antifungal medications are acceptable) * Major congenital malformations, including congenital cleft palate, cytogenetic abnormalities, or serious chronic disorders * Previous immunization with an HPIV2 vaccine * Current use of nasal or systemic steroid medications * Previous serious vaccine-associated adverse event or anaphylactic reaction * Known hypersensitivity to any vaccine component * Lung or heart disease, including reactive airway disease. Participants with clinically insignificant cardiac abnormalities requiring no treatment may be enrolled. Participants who wheezed once or received bronchodilator therapy once in the first year of life but who have not had any additional wheezing episodes or bronchodilator therapy for at least 12 months may also be enrolled. * Member of a household that includes an immunocompromised individual or infants less than 6 months of age * Attends day care with infants less than 6 months of age or immunosuppressed individuals, and parent or guardian is unable or unwilling to suspend daycare for 14 days following immunization. Children who attend facilities that separate children by age and minimize opportunities for transmission of virus through direct physical or aerosol contact are acceptable * Participation in another investigational vaccine or drug trial within 30 days of receiving the investigational vaccine, or while this study is ongoing Inclusion Criteria for Seronegative Infants and Children: * Children and infants 6 to 59 months of age * Parents or guardians can understand and sign the informed consent * Seronegative for HPIV2 antibody, as defined by serum antibody titer HAI ratio less than or equal to 1:8, as determined within 28 days prior to inoculation * History has been reviewed and subject has undergone a physical examination indicating good health * Participant is expected to be available for the duration of the study Exclusion Criteria for Seronegative Infants and Children: * Known or suspected impairment of immunological functions, including maternal history of positive HIV test, receiving immunosuppressive therapy, including systemic corticosteroids or bone marrow/solid organ transplant recipients (topical steroids, topical antibiotics, and topical antifungal medications are acceptable) * Major congenital malformations, including congenital cleft palate, cytogenetic abnormalities, or serious chronic disorders * Previous immunization with an HPIV2 vaccine * Current use of nasal or systemic steroid medications * Previous serious vaccine-associated adverse event or anaphylactic reaction * Known hypersensitivity to any vaccine component * Lung or heart disease, including reactive airway disease. Participants with clinically insignificant cardiac abnormalities requiring no treatment and those who wheezed once or received bronchodilator therapy once in the first year of life but who have not had any additional wheezing episodes or bronchodilator therapy for at least 12 months may be enrolled. * Member of a household that includes an immunocompromised individual or infant less than 6 months of age * Attends day care with infants less than 6 months of age or immunosuppressed individuals, and parent or guardian is unable or unwilling to suspend daycare for 14 days following immunization. Children who attend facilities that separate children by age and minimize opportunities for transmission of virus through direct physical or aerosol contact are acceptable. * Participation in another investigational vaccine or drug trial within 28 days of receiving the investigational vaccine, or while this study is ongoing