This is a Phase 2, randomized, double-blinded study with a 2-arm parallel design. Healthy adults aged 60 through 64 years of age with no history of pneumococcal vaccination will be randomized equally to receive either a single intramuscular dose of multivalent pneumococcal conjugate vaccine followed 1 month later with a dose of saline or Prevnar 13 followed 1 month later with a dose of PPSV23 (control group).