Seventeen JIA patients (International League Against Rheumatism criteria) followed at the Pediatric Rheumatology Unit of Children's Institute of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo and who are refractory to methotrexate [median dose 0.9 mg/kg/week (0.7 - 1)] will be included immediately before the association of anti-TNF (etanercept 0.8 mg/kg/week, Group 1) to the previous therapy. The control group (Group 2) consist of 10 JIA patients on stable dose of methotrexate [median dose 0.8 mg/kg/week (0.3-1.0)]. One intramuscular dose of PPV23 (Sanofi Pasteur), lot B0381-3, at the immunization center of the same hospital will be given to each study subject.