Safety and Immunogenicity of Trivalent Oral Polio Vaccine in Vaccinated Children and Vaccine-Naïve Infants: A Phase 4 Study

In the context of polio eradication, novel oral polio vaccines for type 2 (nOPV2) were developed, and types 1 and 3 polioviruses are being developed. We aimed to generate trivalent oral poliovirus vaccine (tOPV) safety and immunogenicity data as a reference for comparing with novel OPV formulations. This was a single-center, open-label, phase 4 study in March 2016 in the Dominican Republic with healthy children previously vaccinated with ≥3 doses of tOPV receiving one dose of tOPV and vaccine-naïve infants receiving 3 doses of tOPV. Safety and immunogenicity were assessed. No serious adverse reactions or important medical reactions were reported. Seroconversion (SC) rates at Day 28 in children were 32.7%, 36.7%, and 46.9% for types 1, 2, and 3, respectively, and seroprotection (SP) rates 28 days after one dose increased from 89.8% at baseline to 93.9%, 98.0% to 100%, and 83.7% to 98.0% for types 1, 2, and 3, respectively. In infants, SC rates were 88.5%, 98.1%, and 96.2% for types 1, 2, and 3, respectively. SP rates at Day 84 were 93.3%, 100%, and 96.2% for types 1, 2, and 3, respectively. This information can be used as a reference to compare with novel monovalent or trivalent OPVs under development.