The purpose of this study is to learn about the safety and immune effects of a pneumococcal vaccine in adults. This vaccine can possibly provide protection against further pneumococcal disease.
This study will happen in in 2 stages: Stage 1 is seeking participants who are between 18 years to 49 years of age. The participants will receive 1 of 2 pneumococcal vaccine candidates (different formulations) or 20vPnC (Prevnar 20) as a single shot given into the upper arm muscle.
Stage 2 will begin after participants have completed Stage 1, and a pneumococcal vaccine candidate has been decided.
Stage 2 is seeking participants who are adults 50 years of age and older. The participants will receive the chosen pneumococcal vaccine candidate from Stage 1 or 20vPnC (Prevnar 20). The vaccines will be given as a single shot into the upper arm muscle.
Participants will take part in this study for about 6 months for Stage 1 and 12 months for Stage 2. During this time participants will have from 2 to 4 clinic visits and 1 phone visit. At these clinic visits, participants will be asked if any side effects were experienced. The participants will also have to give blood samples during these clinic visits.