Inclusion Criteria:

• Subjects male or female aged 2 to 17 years, inclusive, who weigh ≥ 10 kg at the time of screening and enrollment into the study.
• Subjects with moderately to severely active CD diagnosed at least 1 month before screening, defined by a PCDAI > 30 and an SES-CD > 6 (or an SES-CD ≥ 4 if disease is confined to terminal ileum).
• Subjects who have failed, lost response to, or been intolerant to treatment with at least 1 of the following agents:
  • corticosteroids, immunomodulators (eg, AZA, 6-mercaptopurine, methotrexate), and/or TNF-α antagonist therapy (e.g., infliximab, adalimumab). This includes subjects who are dependent on corticosteroids or exclusive or partial enteral nutrition to control symptoms and who are experiencing worsening of disease in the moderate-to-severe range when attempting to wean off corticosteroids or discontinue exclusive enteral nutrition.
• Subjects with extensive colitis or pancolitis of > 8 years’ duration or left-sided colitis of > 12 years’ duration must have documented evidence of a negative surveillance colonoscopy within 12 months before screening.
• Subjects with vaccinations that are up-to-date based on the countrywide accepted schedule of childhood vaccines.

Exclusion Criteria:

• Subjects who have had previous exposure to approved or investigational anti-integrins, including but not limited to natalizumab, efalizumab, etrolizumab, or AMG 181, or mucosal addressin cell adhesion molecule-1 (MAdCAM-1) antagonists or rituximab.
• Subjects who have had prior exposure to vedolizumab.
• Subjects with hypersensitivity or allergies to any of the vedolizumab excipients.
• Subjects who have received either:
  • an investigational biologic within 60 days or 5 half-lives before screening (whichever is longer); or
  • an approved biologic or biosimilar agent within 2 weeks before the first dose of study drug or at any time during the screening period.
• Subjects with active cerebral/meningeal disease, signs/symptoms or history of progressive multifocal leukoencephalopathy (PML) or any other major neurological disorders including stroke, multiple sclerosis, brain tumor or neurodegenerative disease.
• Subjects who currently require surgical intervention or are anticipated to require surgical intervention for CD during this study.
• Subjects who have had subtotal or total colectomy or have a jejunostomy, ileostomy, colostomy, ileo-anal pouch, known fixed stenosis of the intestine, short bowel syndrome, or > 3 small intestine resections.
• Subjects with a current diagnosis of indeterminate colitis.
• Subjects with clinical features suggesting monogenic very early-onset inflammatory bowel disease.