Objectives A randomized, double-blind, active-controlled noninferiority phase 4 clinical trial was conducted to evaluate the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine (PPV23). Methods Pneumococcal vaccine-naive participants aged ≥2 years were randomly assigned in a 2:1 ratio to receive a single dose of either the treatment vaccine (n=1199) or a comparator vaccine (n=600). We evaluated the immunogenicity before and 30 days post-vaccination, by measuring serum IgG serotype-specific pneumococcal antibodies to 23 serotypes contained in the vaccines via an enzyme-linked immunosorbent assay. The primary outcome was seroconversion (two-fold increase) of serum IgG serotype-specific antibodies at days 30 compared with baseline. Results One month after the administration of PPV23, seroconversion rates for each of the 23 serotypes ranged from 59.22% to 95.67% in the treatment group, and in the control group from 59.66% to 94.07%. The lower bound of the 95% confidence interval (95%CI) of the rate differences for the 23 serotypes were all larger than -10%. Moreover, 12 serotypes (6B, 23F, 1, 2, 4, 8, 9N, 9V, 11A, 15B, 17F and 18C) had a lower bound of 95%CI for rate difference larger than 0. In total, 236 (19.68%) participants in the treatment group and 118 (19.67%) in the control group reported adverse reactions within 30 days poste-vaccination. No significant differences in incidence of adverse reactions were found between the two comparison groups. Conclusions The PPV23 vaccine administered among individual aged ≥2 years was safe, well tolerated and immunogenic, eliciting immune response either comparable to or higher than control vaccine.

Wanqi Yang, Xianying Ye, Zeng Wang, and Dan Yu are employees of Sinovac Biotech. Xinyi Yang and Yuehong Ma are employees of Sinovac Life Sciences. All other authors declare no competing interests. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

NCT05477693

This study was funded by Sinovac Biotech Co., Ltd.

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Ethics Committee of Shaanxi Center for Disease Control and Prevention gave ethical approval for this work (reference no., 2022-001-02)

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