Randomized controlled trial evaluating immunogenicity and safety of a porcine circovirus-free rotavirus vaccine in healthy Chinese infants.

Rotavirus (RV) is a leading cause of diarrhea-related morbidity and mortality among children under 5 y globally, accounting for approximately one-third of childhood diarrhea cases in China. Vaccination is the most effective strategy for RV prevention. Rotarix, a liquid RV vaccine with a 2-dose schedule, has been modified to exclude porcine circovirus (PCV) components. This study evaluated the immunogenicity and safety of Rotarix PCV-free vs Rotarix in healthy Chinese infants. In this Phase III, observer-blinded, randomized, multicenter study, infants aged 6-16 weeks were randomized to receive two oral doses of either vaccine (Rotarix PCV-free or Rotarix) 1-month apart. Primary endpoints were seroconversion rates (SCRs) and geometric mean concentrations (GMCs) of serum anti-RV IgA antibodies 1-month post-Dose 2. Non-inferiority was defined as a 95% CI lower limit (LL) for both SCR ≥ -10% and GMC ratio ≥ 0.67. Safety was assessed by monitoring solicited adverse events (AEs) within 14 d post-vaccination, unsolicited AEs within 31 d, and serious AEs (SAEs) throughout the study. Of 2000 randomized participants, 96.8% (Rotarix PCV-free) and 96.6% (Rotarix) received both doses. SCR: 84.9% (Rotarix PCV‑free) vs 88.7% (Rotarix); difference -3.73% (95% CI - 6.93, -0.55; p = .0317), met non‑inferiority ≥-10%. GMC ratio did not meet non‑inferiority: ratio 0.71 (95% CI 0.60-0.84; p < .0001), 95% CI LL < prespecified 0.67. The most common systemic AE was cough/runny nose (Rotarix PCV-free 30.6% vs Rotarix 25.4%); SAEs occurred in 26.1% and 25.2% of participants, respectively, with none deemed vaccine-related. Rotarix PCV-free demonstrated non-inferior SCRs vs Rotarix. Both vaccines showed comparable safety profiles.ChinaDrugTrials.org registration: CTR2023189.EudraCT: 2020-000972-38.