Efficacy and Safety of Vedolizumab Subcutaneous (SC) as Maintenance Therapy in Crohn's Disease (CD)

The drug being tested in this study is called vedolizumab SC. Vedolizumab SC is being tested to treat people who have moderate to severely active CD. This study will look at clinical remission, as well as enhanced clinical response and corticosteroid-free remission in participants with CD who receive vedolizumab SC maintenance therapy after having achieved a clinical response to vedolizumab IV induction therapy. The study will enroll approximately 824 participants. All participants will enter a 6 week Induction Phase where they will be administered open-label vedolizumab IV 300 mg via IV infusion at Week 0 (Day 1) and Week 2 (Day 15), and will then be assessed for a clinical response at Week 6. Participants who achieve a clinical response at Week 6 will be randomly assigned to one of the two treatment groups: * Vedolizumab SC 108 mg Maintenance Arm * Placebo SC Maintenance Arm Participants who do not achieve a clinical response will not be randomized into the Maintenance Period, and instead will receive a third infusion of vedolizumab IV 300 mg at Week 6. This multi-center trial will be conducted worldwide. The overall time to participate in this study is up to 71 weeks. Participants will make multiple visits to the clinic, plus a final visit 18 weeks after last dose of study drug for a follow-up assessment. Participants will also participate in a long-term safety follow-up, by phone, at 6 months after the last dose of study drug.