Study of a Novel Type 1 Oral Poliomyelitis Vaccine in Bangladesh

This single-center trial is the first clinical assessment of nOPV1 in a pediatric population. It will be a 15-arm, randomized, observer-blind, controlled trial, with Sabin monovalent type 1 vaccine (mOPV1) serving as the control. Enrollment in this pediatric study will be staggered into three age-descending cohorts, Cohort 1 composed of 192 healthy young children 1 to less than 5 years of age who have completed their full routine polio immunization series, Cohort 2 composed of 720 healthy infants 6 weeks of age (+6 days) who will receive only one dose of inactivated poliomyelitis vaccine (IPV) on Day 1, and finally Cohort 3, composed of 1320 healthy poliomyelitis unvaccinated neonates (day of birth +3 days). Participants will receive two or three doses of either nOPV1 at dose levels of 10\^5.5 CCID50, 10\^6.0 CCID50, 10\^6.5 CCID50, 10\^7.0 CCID50 or 10\^7.5 CCID50 or the mOPV control vaccine. The second and third doses of vaccine will be given 28 days following the prior dose. In order to demonstrate the vaccine's ability to reduce fecal shedding following a challenge with the Sabin type 1 strain, the infant cohort will be challenged with mOPV 8 weeks after their last dose of nOPV. Participants will be followed until 28 weeks (young children and neonates) or 32 weeks (infants) after their Day 1 vaccination.