Merck’s pneumococcal vaccine Capvaxive, originally developed and approved for adults over 50, is now showing promise for use in children and adolescents. New data from a phase 3 trial (Stride-13) highlights the vaccine’s ability to provide broader protection against pneumococcal disease in younger patients with chronic medical conditions.
Capvaxive Clinical Trial Results in Children
The phase 3 trial enrolled 882 children ages 2 to 17 who had previously received a pneumococcal vaccination regimen. Results demonstrated:
- Immunogenicity: For 12 serotypes included in Pneumovax 23, immune responses 30 days after vaccination with Capvaxive were comparable. For Capvaxive’s nine unique serotypes, responses were superior to Pneumovax.
- Broader Protection: Capvaxive induced immune responses to all 21 serotypes it covers, measured through opsonophagocytic activity (OPA) geometric mean titers (GMTs).
- Safety: Adverse events, both systemic and vaccine-related, were similar between Capvaxive and Pneumovax, supporting its safety profile.
Expert Insights
Dr. Rotem Lapidot, chief of pediatric infectious diseases at Rambam Health Care Campus and trial investigator, emphasized that children and adolescents with underlying health conditions face higher risks of pneumococcal disease. Capvaxive offers protection against serotypes not included in other childhood pneumococcal vaccines, making it a valuable supplemental option.
Merck’s Paula Annunziato, head of infectious diseases and vaccines development, added that while Capvaxive was designed to target the most invasive adult serotypes, the Stride-13 data underscores its potential to help protect high-risk pediatric patients.
How Capvaxive Compares to Prevnar 20
- Capvaxive: Covers 21 serotypes, representing 84% of pneumococcal disease in adults aged 50+.
- Prevnar 20: Covers 20 serotypes, representing 52% coverage in the same population.
This broader serotype coverage highlights Capvaxive’s competitive edge in both adults and potentially younger populations.
Market Growth and Next Steps
Merck reported Capvaxive sales of $129 million in Q2 2025, up from $107 million in Q1. Findings from the Stride-13 trial were presented at the 6th ESCMID Conference on Vaccines in Lisbon, Portugal, and Merck plans to submit the data to international regulators for further review.
Capvaxive sales are rising, with Merck reporting $129 million in Q2 2025, up from $107 million in Q1 (though this is in the adult market). Your original article’s figures align with market momentum for Merck.
What the New Data Adds & Future Directions
The Stride-13 trial represents a key step in possibly extending Capvaxive’s use to children and adolescents with special medical needs. Should regulators accept these data, Capvaxive may become a supplemental option (beyond standard pediatric PCVs) for broadening pneumococcal protection in high-risk pediatric populations.
Key next steps include:
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Regulatory submission and review: Merck will need to file the pediatric data with agencies (e.g. FDA, EMA) and obtain label extension for under-18 use.
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Longer follow-up: Monitoring durability of immune response, potential need for boosters, and clinical efficacy in children.
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Post-marketing surveillance: Safety monitoring in larger, real-world pediatric populations.
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Guideline adoption: Pediatric and infectious disease societies and immunization advisory bodies would need to evaluate and possibly recommend Capvaxive as a supplemental vaccine for high-risk children.
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Cost-effectiveness analysis: Especially in resource-limited settings, assessing whether additional coverage justifies cost.
In sum, the Stride-13 trial offers promising evidence that Merck’s Capvaxive may safely extend broad pneumococcal protection into younger age groups with chronic conditions—filling gaps left by existing vaccines. If regulatory and guideline hurdles are cleared, Capvaxive could become a valuable tool in pediatric immunization among high-risk groups.
In the coming months, Merck will continue collaborating with global health organizations to assess Capvaxive’s role in national immunization programs. As additional real-world data emerge, the vaccine may become a cornerstone in protecting vulnerable children from pneumococcal disease worldwide. The company’s focus on high-value vaccines positions it well to compete in a global market estimated at more than $10 billion