A Study of Mirikizumab (LY3074828) in Pediatric Participants With Crohn's Disease

Inclusion Criteria: * Participants must have a diagnosis of CD or fistulizing CD, with active colitis, ileitis, or ileocolitis, confirmed at any time in the past by clinical, endoscopic, and histologic criteria. * Participants have moderately to severely active CD (as defined by a baseline PCDAI score ≥30). * Participants must have endoscopy with evidence of active CD defined as SES-CD score ≥6 (or ≥4 for participants with isolated ileal disease) within 1 month of receiving study intervention at Week 0. * Participants must have a documented history of inadequate response, loss of response or intolerance to at least one medication used to treat CD, which may include immunomodulators, oral or IV corticosteroids, a biologic therapy or a JAK inhibitor. Exclusion Criteria: * Participants must not have complications of CD such as symptomatic strictures or stenosis, short gut syndrome, or any other manifestations that might be anticipated to require surgery. * Participants must not have an abscess. * Participants must not have any kind of bowel resection within 26 weeks or any other intra-abdominal surgery within 12 weeks of baseline.