Comparative Efficacy and Safety of 15-Valent and 13-Valent Pneumococcal Conjugate Vaccines Alone and in Combination with the 23-Valent Polysaccharide Vaccine: A Systematic Review and Meta-analysis

In addition to the 23-valent pneumococcal polysaccharide vaccine (PPSV23), the 13-valent and 15-valent pneumococcal conjugate vaccines (PCV13 and PCV15, respectively) are currently utilized as optional vaccines for adults. Although PCV15 provides broader serotype coverage than PCV13, comparative evidence regarding their immunogenicity, safety, and optimal clinical application remains limited. This systematic review and meta-analysis evaluated the immunogenicity and safety of PCV13 and PCV15, both as monotherapy and in combination with PPSV23. We conducted a comprehensive systematic search of PubMed, the Cochrane Library, Web of Science, and ClinicalTrials.gov for randomized controlled trials (RCTs) published through September 15, 2023. Eligible studies included those comparing PCV13 and PCV15, as well as their respective sequential schedules with PPSV23, in adults. Outcomes included opsonophagocytic activity geometric mean titer ratios (OPA GMTRs), immunoglobulin G geometric mean concentration ratios (IgG GMCRs), and adverse event incidence. Risk ratios and 95% confidence intervals were calculated using the inverse variance–weighted method and DerSimonian–Laird random-effects model. Six RCTs (n = 6460) comparing PCV13 and PCV15 monotherapy demonstrated significantly higher OPA GMTRs and IgG GMCRs for the six shared serotypes in the PCV15 group. Injection-site pain and myalgia were more common with PCV15, whereas other adverse events showed no differences. Three RCTs (n = 2279) comparing PPSV23/PCV13 with PPSV23/PCV15 demonstrated higher immune responses for several serotypes in the PPSV23/PCV15 group, with comparable safety profiles. Overall, PCV15 provides broader serotype coverage and elicits robust immunogenicity while maintaining a safety profile comparable to that of PCV13, whether administered as monotherapy or in sequential vaccination with PPSV23.