Immune Response In Children Revaccinated With Pneumococcal Conjugate Vaccine

Inclusion Criteria: * Fully vaccinated children who participated in a previous Wyeth study (Study D139-P506) and received a booster dose of either 23-valent pneumococcal polysaccharide vaccine (PPV23) or pneumococcal conjugate vaccine (PnCV) per the original protocol for that study. * Subjects must be in good health as determined by medical history, physical examination and clinical judgment. Exclusion Criteria: * Known allergy to any component of the 7-valent pneumococcal conjugate vaccine (7vPnC) or 13-valent pneumococcal conjugate vaccine (13vPnC). * History of documented invasive pneumococcal disease (defined as a positive culture of S. pneumoniae from a normally sterile body site). * Any known or suspected disease or dysfunction of the immune system, including: HIV infection, Malignancy, Receipt of immunosuppressive therapy, Sickle cell hemoglobinopathy. * Receipt of immune-globulin within the past 3 months. * Receipt of either PSV or 7vPnCV since the completion of Study D139-P506.