Phase I Study of the Infectivity, Safety and Immunogenicity of Two Recombinant, Live-Attenuated, Bovine/Human, Parainfluenza Virus Type 3 (B/HPIV3) Vectored Vaccines Expressing the Fusion Glycoprotein of Human Metapneumovirus (HMPV), Delivered by Nasal Spray to HPIV3-Seropositive Children 24 to <60 Months of Age
HPIV3 and HMPV are viruses that can cause breathing problems in children. The goal of this clinical trial is to look at the safety of 2 experimental HPIV3/HMPV vaccines in HPIV3-seropositive children ≥ 24 months to \< 60 months of age. Children will receive B/HPIV3/HMPV-PreF-A vaccine, B/HPIV3/HMPV-F-B365 vaccine, or placebo, and participants will not know which study product they have received. The main goals of the study are to find out whether these vaccines are well-tolerated and infectious in HPIV3-seropositive children. The general procedures include daily temperature measurements and daily contact with the participant for the first 28 days, giving a single dose of one of the 2 study vaccines or placebo delivered by nasal sprayer, about 9 in-person visits, a physical examination, 7 clinical assessments, 2 blood samples, 9 nasal swabs and monthly contacts with the participant between Days 29-180. Additional visits may occur if the child has a respiratory illness, fever, or ear infections. The illness visit will include a nasal swab and a clinical assessment.
• ≥24 months of age and \<60 months of age at the time of inoculation
• HAI Screening for HPIV3-neutralizing antibody is obtained within the calendar year of inoculation
• Seropositive for HPIV3 antibody, defined as serum HPIV3 HAI titer \>1:8
• Pre-inoculation serum sample for HPIV3-neutralizing antibody specimen is obtained no more than 42 days prior to inoculation
• In good health based on review of the medical record, history, and physical examination at the time of inoculation
• Received routine immunizations appropriate for age based on the Advisory Committee on Immunization Practices (ACIP) Recommended Immunization Schedule for Children and Adolescents Aged 18 Years or Younger
• Growing normally for age as demonstrated on a World Health Organization (WHO) growth chart, AND has a current height and weight above the 3rd percentile for age
• Expected to be available for the duration of the study
• Parent/guardian is willing and able to provide written informed consent