1236 - Safety and Immunogenicity of a 20-Valent Pneumococcal Conjugate Vaccine (PCV20) in Healthy Infants in the United States

Background: A 20-valent pneumococcal conjugate vaccine (PCV20) is being developed to extend protection against pneumococcal disease beyond that of the 13-valent pneumococcal vaccine (PCV13). This is the first safety and immunogenicity study of PCV20 in healthy infants.

Methods: This randomized, double-blind study enrolled and randomized (1:1) healthy infants ≥ 42 to ≤ 98 days of age to receive a 4-dose series of either PCV20 or PCV13 (control) at 2, 4, 6, and 12 months of age. Local reactions and systemic events were assessed for 7 days after each vaccination; adverse events (AEs) and serious AEs (SAEs) were collected throughout the study. PCV20 immune responses (serotype-specific immunoglobulin G [IgG] and opsonophagocytic activity [OPA]) were measured in sera 1 month after the third infant dose and the fourth dose at 12 months of age.

Results: There were 460 subjects enrolled, with 416 and 391 subjects receiving 3 and 4 doses, respectively. Local reactions and systemic events were predominantly mild to moderate in severity and similar among vaccine groups. There were no related SAEs or deaths reported. PCV20 elicited IgG responses 1 month after the third dose with boosting after a fourth dose. OPA responses were also observed.

Conclusion: PCV20 was well tolerated with a safety profile similar to PCV13. PCV20 elicited immune responses to all 20 vaccine serotypes.