A Study to Assess the Safety, Tolerability, and Immunogenicity of 3 Lots of a Multivalent Pneumococcal Conjugate Vaccine Administered to Adults

The purpose of this study is to provide safety data and demonstrate lot consistency withthe PG4 vaccine by evaluating the immunogenicity of 3 different lots of this vaccine.This study will compare a new pneumococcal vaccine with the vaccine currently in use tosee if they are similarly safe. It will also compare three batches of the new vaccine tomake sure they work the same way. Blood samples will be taken to measure how the bodyresponds to the vaccines.The study will be conducted in the United States. Participants will be assigned to 1 of 4groups. Group 1: PG4 vaccine lot 1; Group 2: PG4 vaccine lot 2; Group 3: PG4 vaccine lot3; Group 4: 20vPnC.Within each group, participants will be assigned by chance in a 2:2:2:1 ratio to receive1 vaccine injection (shot) with either PG4 (new vaccine) lot 1, PG4 lot 2, PG4 Lot 3 or20vPnC, given in the arm. This means that for every 7 participants, about 2 will receiveeither PG4 lot 1, lot 2 or lot 3 and about 1 will receive 20vPnC.Each participant will take part in the study for approximately 6 months.