A Phase 2 Study to Evaluate the Safety, Tolerability, and Immune Response of AFX3772 Vaccine in Healthy Infants

This is a Phase 2 clinical study to support the use of AFX3772 in healthy infants for the prevention of pneumococcal disease. The purpose of this study is to determine the safety, tolerability, and immunogenicity of 3 different formulations of AFX3772 compared with Prevnar 13 (PCV13) and Prevnar 20 (PCV). Part 1 is the dose escalation, lead-in portion of the study in which infants at each dose level will be randomized 3:1 in sequential cohorts of increasing doses of AFX3772 or PCV13. In Part 2, infants will be randomized to receive either one of two dose levels of AFX3772 or PCV20.