Immunogenicity and Safety of a Sabin Strain–Based Inactivated Polio Vaccine: A Phase 3 Clinical Trial

BACKGROUND: The Sabin strain-based inactivated polio vaccine (sIPV) plays a vital role in eradicating poliomyelitis in developing countries. METHODS: The study was designed as a randomized, controlled, double-blinded, noninferiority trial. A total of 1200 healthy infants aged 60-90 days were enrolled and randomly assigned to receive 3 doses of either sIPV (the experimental arm) or IPV (the control arm) at days 0, 30, and 60. Immunogenicity and safety outcomes were assessed using the per-protocol and safety populations, respectively. RESULTS: A total of 553 and 562 participants in the sIPV and IPV groups, respectively, were included in the per-protocol population. Seroconversion rates in the sIPV and IPV groups were 98.0% and 94.1%, respectively, for type 1 poliovirus (P < .01); 94.8% and 84.0%, respectively, for type 2 (P < .01); and 98.9% and 97.7%, respectively, for type 3 (P = .11). A total of 599 and 600 participants in the sIPV and IPV groups, respectively, were included in the safety population. Fever was the most common adverse event, occurring in 61.6% and 49.8% of participants in the experimental and control arms, respectively (P < .01). CONCLUSIONS: The sIPV demonstrated an immunogenicity profile noninferior to that of the conventional IPV and had a good safety profile. CLINICAL TRIALS REGISTRATION: NCT03526978.