Long-term Safety With Vedolizumab Intravenous (IV) in Pediatric Participants With Ulcerative Colitis (UC) or Crohn's Disease (CD)

The drug being tested in this study is called Vedolizumab. Vedolizumab is being tested to treat pediatric participants who have moderately to severely active UC or CD. This study will look at the long-term safety profile in participants who take vedolizumab IV. Participants will continue receiving the same dose assigned from the parent study MLN0002-2003 \[NCT03138655\], which will remain blinded until week 40. The dosing regimen selected for the long-term study is intended to maintain clinical response at the lowest possible exposure. At the discretion of the investigator, participants receiving the low dose (150 or 100 milligram \[mg\]) of vedolizumab IV may be escalated to the high dose (300 or 200 mg) if the participants demonstrate disease worsening at 2 consecutive visits (scheduled or unscheduled). Participants who experience continued disease worsening during the study despite being administered vedolizumab 300 or 200 mg every 8 weeks (Q8W) will be discontinued from the study. Study duration will be until vedolizumab IV is commercially available for pediatric indication(s) in the participant's country or until other drug access programs become available (whichever comes first), the participant turns 18 years of age and can be transitioned to commercial drug, the participant withdraws from the study, or the sponsor decides to close the study (up to approximately 8 years).