After screening, participants will be randomized to ASP3772 or PCV13 on Day 1. A single dose of ASP3772 will be administered on Day 1 as an injection into the right or left thigh muscle at one of three dose levels. The participants randomized to PCV13 will receive a single intramuscular injection of the approved dose of PCV13 into the right or left thigh muscle. All participants will remain at the study site for approximately 30 to 60 minutes following vaccination in order for study site personnel to evaluate any immediate reactions, if needed. The participant's parent/legal guardian will observe for reactions, including daily body temperature measurements and tolerability assessments, from Day 2 through Day 7 and record observed events in the electronic diary device.~All participants will have study visits on Day 7 (+ 1 day) and Day 30 (± 5 days) post-vaccination. The Day 7 visit may be conducted on site or by telephone call.The end-of-study visit will occur on Day 180 (± 14 days), which will be a safety follow-up by telephone call.
The purpose of this 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.