A Study to Evaluate Avacopan in Participants With ANCA-associated Vasculitis

Inclusion Criteria: * Participants has provided informed consent before initiation of any study-specific activities/procedures. * Newly diagnosed or relapse of granulomatosis with polyangiitis or microscopic polyangiitis, consistent with Chapel-Hill Consensus Conference definitions (Jennette et al, 2013), where induction treatment with cyclophosphamide or rituximab is needed. * Age \>/= 18 years (or \>/= legal age within the country if it is older than 18 years). * Positive test for anti-positive antiproteinase 3 or antimyeloperoxidase (current or historic) antibodies. * At least 1 Birmingham Vasculitis Activity Score (BVAS) major item, or at least 3 BVAS nonmajor items, or at least the 2 renal items of proteinuria and hematuria. * eGFR \>/= 15 mL/min/1.73 m\^2 (using Chronic Kidney Disease Epidemiology Collaboration equations). Exclusion Criteria: * Alveolar hemorrhage requiring invasive pulmonary ventilation support anticipated to last beyond the screening period of the study. * Any other known multisystem autoimmune disease that may confound study assessments and study conclusions including but not limited to eosinophilic granulomatosis with polyangiitis (GPA \[Churg-Strauss\]), systemic lupus erythematosus, immunoglobulin (Ig) A vasculitis (Henoch-Schönlein), rheumatoid vasculitis, Sjogren's syndrome, anti-glomerular basement membrane disease, or cryoglobulinemic vasculitis. * Any other medical condition requiring or expected to require continued use of immunosuppressi…