This single-center trial is is the first clinical assessment of nOPV1 in a pediatric population. It will be a 12-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 336 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 1155 healthy poliomyelitis unvaccinated neonates (day of birth +3 days). Participants will receive two doses of either nOPV1 at dose levels of 10^5.5 CCID50, 10^6.0 CCID50 or 10^6.5 CCID50, or the mOPV control vaccine. The second dose of vaccine will be given 28 days following the first 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 the second vaccine dose. Participants will be followed until 28 weeks (young children and neonates) or 32 weeks (infants) after their Day 1 vaccination.
The purpose of this clinical trial is to assess the safety and tolerability (primary objective), immunogenicity (primary and secondary objectives), fecal shedding of vaccine viruses (secondary objective) and the potential for neurovirulence of shed virus (secondary objective) of a novel oral polio type 1 vaccine, nOPV1, as compared to Sabin monovalent type 1 vaccine controls (mOPV1), in healthy young children (192 subjects), infants (336 subjects), and neonates (1155 subjects).