The purpose of this study is to assess the "late" immune response to further doses of pneumococcal conjugate vaccine more than 10 years after primary immunization with Prevnar (7vPnC) in infancy, as compared with individuals who did not receive Prevnar in infancy (the Prevnar naive cohort which received MnCC). The study will take place at a single study center. Study participants must have participated previously in a specific Wyeth Prevnar study (Study D118-P8) and must still be enrolled in the Northern California Kaiser Permanente (NCKP) health plan.