RAHWAY, N.J., June 18, 2026
Merck announced that the U.S. Food and Drug Administration (FDA) has approved an expanded indication for CAPVAXIVE® (Pneumococcal 21-valent Conjugate Vaccine) for children and adolescents aged 2 through 17 years who have completed a primary pneumococcal vaccination series and have chronic medical conditions that increase their risk of pneumococcal disease. With this approval, CAPVAXIVE becomes the only pneumococcal conjugate vaccine (PCV) specifically studied and indicated in the United States for this high-risk pediatric population. The expanded label allows the vaccine to provide additional serotype coverage beyond currently approved pediatric PCV series, offering broader protection against invasive pneumococcal disease caused by Streptococcus pneumoniae.
Phase 3 STRIDE-13 Trial Demonstrated Strong Immunogenicity and Safety
The FDA approval is supported by results from the Phase 3 STRIDE-13 (NCT06177912) trial, a randomized, double-blind, active comparator-controlled study involving 874 children and adolescents aged 2–17 years with chronic conditions including diabetes, chronic heart disease, chronic kidney disease, chronic liver disease, and chronic lung disease. Participants previously completed a standard pediatric pneumococcal vaccination series and were randomized to receive either a single dose of CAPVAXIVE or PPSV23. The study demonstrated that CAPVAXIVE was noninferior to PPSV23 across all 12 shared serotypes while producing statistically superior immune responses for the nine serotypes unique to CAPVAXIVE. The vaccine also generated protective immune responses against serotype 15B, which is cross-reactive with serotype 15C. The safety profile was generally comparable to PPSV23, with injection-site pain, fatigue, headache, erythema, swelling, malaise, and irritability being the most frequently reported adverse reactions.
Expanded Protection for Children at Elevated Risk
Children with chronic medical conditions face a significantly higher risk of developing invasive pneumococcal disease (IPD), including pneumonia, meningitis, and bloodstream infections. According to CDC epidemiological data cited by Merck, CAPVAXIVE covers approximately 79% of invasive pneumococcal disease cases in high-risk pediatric populations, with its 11 additional serotypes accounting for nearly 40% of cases not addressed by current pediatric conjugate vaccines. Although these epidemiological estimates do not represent direct vaccine efficacy, the broader serotype coverage highlights CAPVAXIVE’s potential to address important gaps in protection for vulnerable children and adolescents. Merck noted that CAPVAXIVE is intended to complement—not replace—the existing pediatric pneumococcal vaccination schedule by providing additional protection after completion of the primary vaccine series.
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Merck Expands CAPVAXIVE Across Multiple Age Groups
Originally developed for adults, CAPVAXIVE is a 21-valent pneumococcal conjugate vaccine administered as a single-dose immunization and was specifically designed to target serotypes responsible for the majority of invasive pneumococcal disease. In adults aged 50 years and older, the vaccine covers serotypes responsible for approximately 82% of IPD cases, including eight serotypes not covered by PCV20, based on CDC surveillance data. With the new pediatric indication, Merck continues to expand CAPVAXIVE’s role in preventing serious pneumococcal infections across different age groups. The approval reinforces the company’s commitment to addressing unmet needs in infectious disease prevention through broader vaccine coverage for individuals at elevated risk.
Source: Merck, press release
