A Study of Vedolizumab in Adult Participants With Moderate to Severe Crohn's Disease

Inclusion criteria: 1. The participant has a diagnosis of CD established at least 3 months before screening by clinical and endoscopic evidence corroborated by a histopathology report. Cases of CD established at least 6 months before randomization for which a histopathology report is not available will be considered based on the weight of evidence supporting the diagnosis and excluding other potential diagnoses, and must be discussed with the sponsor on a case-by-case basis before randomization. 2. The participant has moderately to severely active CD as determined by a 2-component patient-reported outcome (PRO2) score of 14 to 34 points and a Simple Endoscopic Score for Crohn's Disease (SES-CD) score of ≥6 (or ≥4 in cases of isolated ileitis) on screening ileocolonoscopy. 3. The participant has CD involvement of the ileum and/or colon, at a minimum. 4. A participant with extensive colitis or pancolitis of \>8 years duration or limited colitis of \>12 years duration must have documented evidence that a surveillance colonoscopy was performed within 12 months before initial screening (may be performed during screening if not performed in previous 12 months). 5. A participant with a family history of colorectal cancer, personal history of increased colorectal cancer risk, age \>50 years, or other known risk factor must be up-to-date on colorectal cancer surveillance (may be performed during screening). 6. The participant has demonstrated an inadequate response to, loss of response to, or intolerance of at least 1 of the following agents as defined below: * Corticosteroids. * Immunomodulators. * TNF-α antagonists. Exclusion Criteria: I. Gastrointestinal (GI) Exclusion Criteria: 1. The participant has evidence of abdominal abscess at the initial screening visit. 2. The participant has had extensive colonic resection, subtotal or total colectomy. 3. The participant has a history of \>3 small bowel resections or diagnosis of short bowel syndrome. 4. The participant has received tube feeding, defined formula diets, or parenteral alimentation within 21 days before administration of the first dose of study drug. 5. The participant has had ileostomy, colostomy, known fixed symptomatic stenosis of the intestine, or evidence of fixed stenosis, or small bowel stenosis with prestenotic dilation. 6. Within 30 days before randomization, the participant has received any of the following for the treatment of underlying disease: * Nonbiologic therapies (eg, cyclosporine, thalidomide) other than those specifically listed in the Permitted Medications and Treatments section. * An approved or investigational nonbiologic therapy in an investigational protocol. 7. The participant has received traditional Chinese medication (TCMs) within 30 days before randomization. 8. The participant has had previous exposure to approved or investigational anti-integrins including, but not limited to natalizumab, efalizumab, etrolizumab, or abrilumab (AMG-181), or mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) antagonists, or rituximab. 9. The participant has had previous exposure to vedolizumab. 10. The participant has used topical (rectal) treatment with 5-aminosalicylic acid (5-ASA), corticosteroid enemas/suppositories or traditional Chinese medications for CD treatment within 2 weeks of the administration of the first dose of study drug. 11. The participant requires currently or is anticipated to require surgical intervention for CD during the study. 12. The participant has a history or evidence of adenomatous colonic polyps that have not been removed. 13. The participant has a history or evidence of colonic mucosal dysplasia including low or high-grade dysplasia, as well as indeterminate for dysplasia. II. Infectious Disease Exclusion Criteria 14. The participant has evidence of active infection during the screening period. 15. The participant has evidence of treatment for Clostridioides difficile (C difficile) infection or other intestinal pathogen within, 28 days before first dose of study drug. 16. The participant has chronic hepatitis B virus (HBV) infection or chronic hepatitis C virus (HCV) infection. 17. The participant has active or latent tuberculosis (TB). 18. The participant has any identified congenital or acquired immunodeficiency (eg, common variable immunodeficiency, human immunodeficiency virus \[HIV\] infection, organ transplantation). 19. The participants has received any live vaccinations within 30 days before screening. 20. The participant has a clinically significant active infection (eg, pneumonia, pyelonephritis, or coronavirus disease 2019 \[COVID-19\]) within 30 days before screening or during screening, or has an ongoing chronic infection or any ongoing COVID-19-related symptom(s), if previously diagnosed as having COVID-19. III. General Exclusion Criteria 21. The participant has had any surgical procedure requiring general anesthesia within 30 days before enrollment or is planning to undergo major surgery during the study period. 22. The participant has any history of malignancy, except for the following: (a) adequately-treated nonmetastatic basal cell skin cancer; (b) squamous cell skin cancer that has been adequately treated and has not recurred for at least 1 year before randomization; and (c) history of cervical carcinoma in situ that has been adequately treated and has not recurred for at least 3 years before randomization. Participants with remote history of malignancy (eg, \>10 years since completion of curative therapy without recurrence) will be considered based on the nature of the malignancy and the therapy received and must be discussed with the sponsor on a case-by-case basis before randomization. 23. The participant has a history of any major neurological disorders, including stroke, multiple sclerosis, brain tumor, or neurodegenerative disease.