Patient description: A 57-year-old man was admitted to the clinic because of weight loss and persistent dry cough 4 months ago. Chest computed topography showed bilateral multiple infiltrates in the upper lobes and thickened bronchial walls. There is a documented positive serum MPO-ANCA in his medical record. Transbronchial biopsy revealed necrotic granulomas with multinucleated giant cells and the Wegener's granulomatosis was diagnosed for him. He is treating with corticosteroid and cyclophosphamides since 4 months ago. His Birmingham Vasculitis Activity Score (BVAS) is above 4 since the beginning of his disease. His last physical exam and lab study was performed yesterday and showed the results bellow: A wellbeing, well-nourished man, non-icteric, cooperative and alert Weight: 73 kg Height: 177 BP: 120/80 HR: 90/min RR: 22/min Hgb: 13 g/dl WBC: 8000 /mm3 (Neutrophil: 2700/mm3) Plt: 300000 /ml AST: 40 U/L ALT: 56 U/L Alk P: 147 U/L Bill total: 1.2 mg/dl ESR: 120 mm/hr MPO-ANCA: 153 EU

Clinical trial eligibility criteria: eligible ages (years): 40.0-999.0,  Systemic Vasculitis To be included in the trial all participants must Have given written informed consent to participate Be aged 40 years and over For patients in Group 1 only (rituximab treated) Have a diagnosis of AAV [granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) or eosinophilic granulomatosis with polyangiitis (eGPA)] Have current or historical PR3/MPO ANCA positivity by ELISA or histological confirmation of AAV Have received ≥ 2g rituximab Have received their last dose of rituximab at least 12 months prior to enrolment Be in stable remission with a prednisolone dose of ≤ 5mg/day For patients in Group 2 only (disease controls who have never received rituximab) Have a diagnosis of AAV (GPA, MPA or eGPA) Have current or historical PR3/MPO ANCA positivity by ELISA or histological confirmation of AAV  The presence of any of the following will preclude participant Age < 40 years History of severe allergic or anaphylactic reactions to pneumococcal vaccinations Pneumococcal vaccination within 5 years prior to screening Females who are pregnant, plan to become pregnant, or breast feeding Medical, psychiatric, cognitive or other conditions that, in the investigator's opinion, compromise the patient's ability to understand the patient information, give informed consent, comply with the trial protocol, or to complete the study History of malignancy within the past five years or any evidence of persistent malignancy, except fully excised basal cell or squamous cell carcinomas of the skin, or cervical carcinoma in situ which has been treated or excised in a curative procedure Replacement immunoglobulin (IVIg) administered intravenously or subcutaneously in the 12 weeks prior to screening visit. For patients in Groups 1 and 2 only (AAV patients) Presence of another multisystem autoimmune rheumatic disease The prior receipt of more than 36g of cumulative cyclophosphamide ever (either IV or oral) For patients in group 1 only (rituximab group) • The receipt of any immune suppressing agent (azathioprine, methotrexate or mycophenolate mofetil) after rituximab For patients in Group 2 only (disease controls)