Immunogenicity and Safety of Sabin Strain Inactivated Poliovirus Vaccine Booster Dose Administered Separately or Concomitantly with Inactivated Hepatitis A Vaccine or Measles-Mumps-Rubella Combined Attenuated Live Vaccine: An Open-Labelled, Randomized, Controlled, Phase 4 Clinical Trial.

OBJECTIVES: To determine whether a Sabin strain inactivated poliovirus booster (sIPV) given concomitantly (same day, different sites) with MMRV or inactivated hepatitis A vaccine (HepA) is non-inferior in immunogenicity and comparable in safety to separate administration at the 18-month visit. METHODS: Open-label, randomized Phase IV trial in healthy children (18~22 months), allocated 2:2:2:1:1 to sIPV&MMRV, sIPV&HepA, sIPV-only, MMRV-only, or HepA-only. Primary endpoints were Day-30 seroconversion rates (SCRs) for poliovirus types 1-3 (sIPV arms) and for HepA (HepA arms). RESULTS: Of 892 screened, 889 were randomized; baseline characteristics were balanced. By Day 30, seroprotection was 100% for PV types 1-3 in all sIPV-containing arms. SCRs were high and similar across concomitant vs. separate administration; all pairwise SCR differences met non-inferiority (-10% margin). Adjusted post-vaccination GMTs were comparable across serotypes. For HepA, Day-30 SPoR was 99.3% vs. 100.0%, and adjusted GMC was 412.2 vs. 465.9 (p = 0.2224). For MMRV, Day-30 SPoR was 100% in both groups with similar adjusted GMCs. Within 30 days, overall adverse reactions were 14.5%/17.4%/16.3%/7.3%/10.8% (sIPV&MMRV/sIPV&HepA/sIPV-only/MMRV-only/HepA-only), mostly mild to moderate; no vaccine-related SAEs (NCT06442449). CONCLUSIONS: Same-day sIPV co-administration with MMRV or HepA was non-inferior and well tolerated, supporting programmatic adoption.