Recombinant Trivalent Poliomyelitis Vaccine (Sf-RVN Cell) (CanSino Biologics)

This is a phase I/II randomized, double-blind, and positive-controlled study. Participants in the phase I toddler group will receive 1 dose of either high dose VLP-Polio (Dose H) or control vaccine in a ratio of 3:1. The phase I infant cohort will have 4 arms randomly assigned to receive either investigational vaccine (Low-adjuvant dose VLP-Polio, Medium dose VLP-Polio, or High dose VLP-Polio or control vaccine in a ratio of 3:1. Phase II infant cohort will have 4 arms randomly assigned to receive either investigational vaccine (Low-adjuvant dose VLP-Polio, Medium dose VLP-Polio, or High dose VLP-Polio or control vaccine in a ratio of 3:1. Each infant participant will be administrated 3 doses of the assigned vaccine with 28 days apart, and the booster dose will be given when the infant is 12-18 months old. Enrollment of Phase I and Phase II will be staggered in descending order of age group but ascending order of dosing levels. Blood and mucosal samples will be collected for immunogenicity evaluation over the time course of the study.