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

Merck’s pneumococcal 21-valent conjugate vaccine (Capvaxive) demonstrated immune responses to all 21 serotypes assessed by serotype-specific opsonophagocytic activity geometric mean titers 30-days after vaccination. In STRIDE-13 (NCT06177912), investigators evaluated the safety, tolerability, and immunogenicity of Capvaxive compared with pneumococcal 23-valent polysaccharide vaccine (PPSV23) for children and adolescents aged 2 to less than 18 years who have completed a primary pediatric pneumococcal vaccination regimen and have 1 or more chronic conditions that are risk factors for pneumococcal disease.¹

Merck’s pneumococcal 21-valent conjugate vaccine was noninferior to the pneumococcal 23-valent polysaccharide vaccine for all 12 shared serotypes and superior to 9 unique serotypes. | Image Credit: kittisak - stock.adobe.com

“Children and adolescents living with chronic medical conditions are at increased risk of pneumococcal disease and offering them additional protection is essential,” Rotem Lapidot, MD, chief of pediatric infectious diseases at Rambam Health Care Campus, said in a news release.¹ “Results from STRIDE-13 demonstrate the potential of Capvaxive to deliver protection for these vulnerable populations, who may benefit from additional pneumococcal disease coverage by including serotypes not contained in other approved pneumococcal infant regimens.”

In the study, investigators included children and adolescents who had 1 or more of the following conditions for at least 3 months: diabetes, chronic compensated liver disease, chronic lung disease, chronic heart disease, or chronic kidney disease. Patients also completed a pneumococcal conjugate vaccine regimen—including PCV7, PCV10, or PCV13—at least 8 weeks prior to study enrollment. Patients received one dose of either Capvaxive or PPSV23. There were 882 individuals included in the study.^1,2

The primary outcomes included the percentage of individuals with injection site adverse events (AEs), solicited systemic AEs, and vaccine-related serious AEs, as well as geometric mean titers of serotype-specific responses. Secondary outcomes include geometric mean concentrations of serotype-specific immunoglobulin G, geometric mean fold rise, and percentage of individuals with a 4-fold or greater rise.²

Capvaxive showed noninferiority to PPSV23 for all 12 of the shared serotypes and the vaccine was also superior to PPSV23 for the 9 unique serotypes to Capvaxive at 30 days postvaccination. Furthermore, investigators found that the rates of AEs, including systemic and serious vaccine-related AEs, were comparable between both vaccine groups.¹

“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 the news release.¹ “We are encouraged by the safety and immunogenicity data presented at the 6th ESCMID Conference on Vaccines, which underpin our commitment to ensuring infants and adults have access to protection against invasive pneumococcal disease.”

In STRIDE-10 (NCT05569954), Capvaxive was noninferior to PPSV23 for all 12 common serotypes and superior for 9 unique serotypes in patients 50 years and older who were pneumococcal vaccine naïve. The most frequently reported AEs were injection site pain, headache, fatigue, injection site erythema, and myalgia, according to the results.³

READ MORE: Pneumococcal Resource Center

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REFERENCES

1. Capvaxive (pneumococcal 21-valent conjugate vaccine) demonstrates positive immune responses in children and adolescents at increased risk of pneumococcal disease. News release. Merck. September 11, 2025. Accessed September 15, 2025. https://www.merck.com/news/capvaxive-pneumococcal-21-valent-conjugate-vaccine-demonstrates-positive-immune-responses-in-children-and-adolescents-at-increased-risk-of-pneumococcal-disease/

2. A clinical study of the v116 vaccine for children and teenagers (V116-013) (STRIDE-13). ClinicalTrials.gov identification: NCT06177912. Updated March 24, 2025. Accessed September 15, 2025. https://clinicaltrials.gov/study/NCT06177912?intr=v116&rank=1

3. Gallagher A. V116 pneumococcal vaccine shows noninferiority to PPSV23. Drug Topics. May 21, 2025. Accessed September 15, 2025. https://www.drugtopics.com/view/v116-pneumococcal-vaccine-shows-noninferiority-to-ppsv23