The purpose of this Phase 1 study is to evaluate the safety and tolerability of three dose levels of ASP3772 in comparison to the active comparator Prevnar 13® (PCV13) in toddlers who have previously been administered the routine three-dose series of PCV13.

This study will also evaluate the immunogenicity (production of an immune response) of three different dose levels of ASP3772 in comparison to the active comparator PCV13 in toddlers who have previously been administered the routine three-dose series of PCV13.