Pneumococcal: Most-Read Stories of 2025

Pneumococcal prevention is entering a sophisticated new chapter where valency, cost, and age-specific epidemiology intersect. This year’s top stories highlight a shifting landscape: while newer vaccines offer broader serotype coverage, their long-term cost-effectiveness is being challenged by the success of childhood herd immunity.

Here are the most-read pneumococcal stories of 2025, plus you can read all of our pneumococcal coverage here.

Cost-Effectiveness of PCV15, 20 Vaccines Expected to Decrease

While pneumococcal conjugate vaccine 15-valent and 20-valent (PCV15 and PCV20) are more effective at reducing disease and mortality in older adults, their long-term cost-effectiveness is expected to decrease, according to a study published in Expert Review of Vaccines. This shift is primarily attributed to indirect herd immunity generated by childhood vaccination programs, which naturally lowers the disease burden among the elderly. While PCV15 and PCV20, separate, were more effective than the current PPV23 vaccination program in Ontario, Canada, the disease burden and mortality reduction came at a higher cost than the currently accepted immunization program.

Pneumococcal Disease Concerns Remain Despite Successful Vaccine Introduction

Despite the success of national immunization programs, the burden of pneumococcal disease remains high due to shifting serotypes, according to findings published in Human Vaccines & Immunotherapeutics. Researchers found that serotype 3 remains a persistent threat globally, while serotype 4 is reemerging in specific populations across North America. To combat these trends, the authors stressed the need for localized surveillance and higher vaccine uptake—particularly for high-risk and older adults—to ensure that the latest higher-valency conjugate vaccines are utilized where they are most needed.

Pneumococcal Serotype Can Determine Clinical Disease Outcomes

A meta-analysis published in Frontiers in Medicine has identified that the risk of death from invasive pneumococcal disease (IPD) is heavily dependent on the infecting serotype. Researchers found that serotype 31 carried the highest case fatality rate at 31.4%. Other serotypes more likely to cause mortality included 3, 6A, 11A, 15A, and 19F.

“Expanding vaccine coverage to include additional serotypes could further reduce the overall burden of pneumococcal disease. Our crucial finding about risk of death for some NVTs [nonvaccine serotype] is vital to inform their inclusion recent higher-valent formulations,” the study authors wrote. “Acknowledging that epidemiological data is key in selecting vaccine serotypes, our results, as well as the individual studies included provide enough evidence to consider incorporating serotype 31, and 15A into vaccine formulations.”

PCV24 Is Clinically, Economically Unfavorable Compared With PCV21

PCV21 (Capvaxive) is the most effective and cost-effective vaccine for adults aged 65 and older, "dominating" newer options like PCV24, according to research published in the American Journal of Preventive Medicine. While PCV24 covers more serotypes, PCV21 is specifically formulated based on adult disease epidemiology, allowing it to bypass the diminishing returns caused by childhood herd immunity. Furthermore, PCV21 was shown to substantially decrease disparities in disease risk between Black and non-Black participants, making it the most logical choice for addressing both clinical outcomes and health equity.

Capvaxive Shows Immune Responses to All 21 Serotypes for Children, Adolescents

Capvaxive (PCV21) elicited a robust immune response across all 21 included serotypes in children and adolescents with chronic medical conditions, according to data from the STRIDE-13 trial. The vaccine proved noninferior to the standard PPSV23 for shared serotypes and demonstrated superior protection for 9 unique strains, all while maintaining a comparable safety profile.

“While Capvaxive was designed to specifically cover the serotypes that cause the majority of invasive pneumococcal disease cases in adults, findings from STRIDE-13 underscore its added potential to help protect children and adolescents who are at an increased risk,” Paula Annunziato, MD, senior vice president of infectious diseases and vaccines in global clinical development at Merck Research Laboratories, said in a news release.