To evaluate the immunological memory against pneumococcal vaccine serotypes in children primed with conjugate vaccines by administering a booster dose of plain polysaccharide vaccine.

2 groups (60 per group), booster of Pneumovax 23 after priming with Prevnar or GSK Biologicals' pneumococcal vaccine.

Inclusion:

• healthy children between 11-14 months old who received primary vaccination with Prevnar or GSK Biologicals' pneumococcal conjugate vaccine.

Exclusion:

• children having received or planning to receive any investigational products, vaccines not foreseen in the protocol and immune modifying drugs;
• children having received any additional pneumococcal vaccine than in the primary study;
• children with any disease that affect the immune system and history of seizures and/or allergic disease.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.