Immunogenicity and safety of 20-valent pneumococcal conjugate vaccine in pneumococcal vaccine–naive adults ≥18 years of age in India: A phase 3 single-arm trial

<i>Streptococcus pneumoniae</i> is a leading cause of bacteremia, bacterial meningitis, and pneumonia. In India, there is an unmet need for an expanded valent pneumococcal conjugate vaccine (PCV) to protect older adults. This phase 3, single-arm study evaluated the safety and immunogenicity of 20-valent PCV (PCV20) in adults ≥18 y of age in India. Participants were enrolled into two age groups (18‒49 and ≥50 y old) and received a single dose of PCV20. Immunogenicity endpoints included geometric mean fold rises (GMFRs) in pneumococcal serotype-specific opsonophagocytic activity (OPA) titers from before to 1 month after vaccination. Safety endpoints included percentages of participants reporting local reactions and systemic events within 7 d after vaccination and adverse events (AEs) and serious AEs within 1 month after vaccination. All 400 participants (200 in each age group) received a single dose of PCV20. OPA geometric mean titers substantially increased from baseline to 1 month after PCV20 vaccination for all 20 serotypes. Overall, GMFRs ranged from 5.9 (serotype 14) to 49.8 (23F) for PCV13 serotypes and from 5.4 (11A) to 75.7 (12F) for the 7 additional PCV20 serotypes. Most local reactions and systemic events were mild or moderate in severity and transient. Overall, 2.3% of participants reported any AE through 1 month after vaccination. No related, immediate, severe, or serious AEs were reported. Consistent with previous trials, PCV20 elicited robust immune responses to all 20 serotypes following a single dose and was well tolerated with an acceptable safety profile in Indian adults ≥18 y of age. NCT05875727.