A phase 3, multicenter, single-arm, open-label study to assess the safety, tolerability, and immunogenicity of a single dose of 13-valent pneumococcal conjugate vaccine in Japanese participants aged 6–64 years who are considered to be at increased risk of pneumococcal disease and who are naive to pneumococcal vaccines

•PCV13 use was studied in Japanese subjects aged 6–64 years at increased risk for pneumococcal disease.•PCV13 was well tolerated with an acceptable safety profile; no serious adverse events occurred.•Robust immune responses were observed 1 month after PCV13 vaccination.•Opsonophagocytic activity and IgG geometric mean fold rises assessed immune responses.•These data support PCV13 use in Japanese subjects aged 6–64 years at increased risk for pneumococcal disease. This open-label, single-arm, phase 3 study evaluated safety and immunogenicity of the 13-valent pneumococcal conjugate vaccine (PCV13) in pneumococcal vaccine-naive Japanese individuals aged 6–64 years at increased risk of pneumococcal disease (PD). Participants received 1 PCV13 dose. Reactogenicity events were recorded for 7 days (individuals aged 6- to 17-year-old) or 14 days (individuals aged 18 to 64 years old) postvaccination. Adverse events (AEs) were collected for 1 month postvaccination. Opsonophagocytic activity (OPA) and anticapsular immunoglobulin G (IgG) geometric mean concentrations (GMCs) were measured for vaccine serotypes before and 1 month postvaccination. Post hoc analyses compared immunogenicity in participants categorized as at-risk (immunocompetent but having chronic medical conditions associated with increased PD risk) or high-risk (immunocompromised due to diseases/conditions and/or medications). 206 participants aged 6- to 17-year-old (n = 53) and 18 to 64 years old (n = 153) completed the study. Reactogenicity events were generally mild to moderate in severity. AEs were reported in 16% (33/206) of participants; 1.0% (2/206) were severe. Six AEs were vaccine-related; most were associated with local reactions. No serious AEs occurred. Circulating antibody levels for all 13 serotypes increased postvaccination. OPA geometric mean fold rises (GMFRs) from prevaccination to 1 month postvaccination were 5.5–61.7; lower limits of the 2-sided, 95% CI were > 1 for all serotypes. IgG GMFRs were consistent with OPA analyses. In post hoc analyses, 55.8% (115/206) and 44.2% (91/206) of participants were categorized as at risk and at high risk of PD, respectively; OPA GMFRs from prevaccination to 1 month postvaccination were 3.9–635.1, with lower limits of the 2-sided 95% CIs > 1 for all 13 serotypes across these risk groups; IgG GMFRs were consistent with OPA analyses. PCV13 was well tolerated and immunogenic in Japanese individuals aged 6–64 years considered at increased risk of PD. Res