Clinical, laboratorial and therapy assessment: All patients will be evaluated on the day of vaccination, 2 months and 12 months after immunization for clinical and laboratorial parameters: number of active joints (swelling within a joint, or limitation in the range of joint movement with joint pain or tenderness), number of limited joints, morning stiffness, patient and physician global assessment of arthritis activity measured with pain scores on the Visual Analog Scale" (VAS) and validated Brazilian version of Childhood Health Assessment Questionnaire (CHAQ). Erythrocyte sedimentation rate (ESR) was evaluated according to Westergreen method and C-reactive protein (CRP) according to nephelometry. The Juvenile Arthritis Disease Activity Score with 27-joint reduced count (JADAS-27), defined as the linear sum of the scores of 4 components [physician global assessment of disease activity (measured on a 10-cm VAS), parent/patient global assessment of well-being (measured on a 10-cm VAS); number of active joints (0-27 joints); and ESR] (range: 0 - 57 points), will be calculated in all JIA patients. Current concomitant treatment with non-steroidal anti-inflammatory drug, prednisone, methotrexate, leflunomide and cyclosporine will be evaluated.