The Safety and Immunogenicity of a 13-Valent Pneumococcal Polysaccharide Conjugate Vaccine (CRM197/TT) in 12–23-Month Children: A Double-Blind, Randomized, Phase III Trial in China

<b>Objectives</b>: This study systematically assessed the safety and immunogenicity of a new 13-valent pneumococcal conjugate vaccine (CRM197/TT, PCV13i) against the licensed PCV13 vaccine in a cohort of Chinese children between 12 and 23 months of age. <b>Methods</b>: This is a phase III, randomized, double-blind trial (NCT04841369). A total of 528 participants were randomized 1:1 to receive two doses of either PCV13i experimental or the PCV13 control vaccine at a 2-month interval, with 517 participants completing the vaccinations. <b>Results</b>: The overall incidence of adverse events (37.12% vs. 32.70%, <i>p</i> = 0.134) and adverse reactions (24.81% vs. 21.61%, <i>p</i> = 0.221) was comparable between the experimental and control groups. Local adverse reactions were more frequent in the experimental group (10.00% vs. 6.12%, <i>p</i> = 0.021), such as erythema (7.88% vs. 4.02%, <i>p</i> = 0.008). Systemic adverse reactions, including fever (10.77% vs. 13.77%), showed no significant differences. No vaccine-related serious adverse events occurred. Immunogenicity assessments showed that seropositivity rates for most serotypes reached ≥96% in both groups, with eight serotypes achieving 100% seropositivity in the experimental group. PCV13i induced higher IgG geometric mean concentrations (GMCs) for serotypes 3, 7F, and 19F (<i>p</i> < 0.05), whereas the control group showed higher GMCs for serotypes 1, 5, 6A, and 14 (<i>p</i> < 0.05). Opsonophagocytic activity (OPA)-related geometric mean titers (GMTs) were superior for PCV13i against serotypes 7F (39,583 vs. 17,249, <i>p</i> < 0.001) and 19F (1517 vs. 983, <i>p</i> = 0.028), but lower for serotype 5 (13 vs. 93, <i>p</i> < 0.001). <b>Conclusions</b>: PCV13i demonstrated non-inferior immunogenicity and an acceptable safety profile in 12-23-month-old children.