Ulcerative Colitis (UC) and Crohn's Disease (CD) are conditions that affect the gut and can cause symptoms like diarrhea, inflammation, and belly pain. This study is testing a medicine called Vedolizumab to see if it helps these symptoms go away. People in the study will take Vedolizumab for about 1 year.

At first, the medicine is given through a vein in the arm (intravenously) for the first 6 weeks, and then it's given as a shot under the skin (subcutaneously). If the medicine doesn't work after 3.5 months, participants can stop and try something else. Check-ups will happen at 6 months and 1 year, and again 4.5 months after stopping the medicine.

• Study lasts about 1 year with several clinic visits.
• Initial treatment is intravenous, then subcutaneous.
• Some participants may stop early if treatment is ineffective after 3.5 months.