A Phase 3, Single-arm Trial to Evaluate the Safety and Immunogenicity of a 20-Valent Pneumococcal Conjugate Vaccine in Healthy Children 15 Months Through <18 Years of Age

Background: A 20-valent pneumococcal conjugate vaccine (PCV20), containing 13-valent PCV (PCV13) components and 7 additional polysaccharide conjugates, was developed to extend protection for pneumococcal disease. This phase 3 study assessed the safety and immunogenicity of PCV20 in children. Methods: In this single-arm study, children (>= 15 months-<18 years of age) received 1 dose of PCV20. Children <5 years of age had >= 3 prior doses of PCV13; children >= 5 years were recruited regardless of previous PCV receipt. Serotype-specific IgG concentrations and opsonophagocytic activity (OPA) titers were measured before and 1 month after PCV20. Local reactions and systemic events, adverse events (AEs), serious AEs, and newly diagnosed chronic medical conditions were collected. Results: Of 839 enrolled participants, 831 (>99%) were vaccinated, and 819 (>97%) completed all study visits. Local reactions and systemic events were mostly mild to moderate in severity. No serious AEs were considered PCV20-related. IgG geometric mean fold rises (GMFRs) from before to 1 month after PCV20 ranged from 27.9-1847.7 (7 additional serotypes) and 2.9-44.9 (PCV13 serotypes) in children <5 years of age, and 10.5-187.7 (7 additional serotypes) and 4.3-127.9 (PCV13 serotypes) in children >= 5 years old. OPA GMFRs from before to 1 month after PCV20 ranged from 12.4-983.6 to 2.8-52.9 in children <5 years of age and from 11.5-499.0 to 5.3-147.9 in children >= 5 years of age. Conclusions: Among children >= 15 months through <18 years of age, PCV20 was well tolerated and induced robust responses to all 20 serotypes, supporting the use of PCV20 in children.