Vedolizumab is a medicine that helps to reduce inflammation and pain in the digestive system. In this study, children and teenagers with moderate to severe Crohn's disease will be treated with vedolizumab.
The main aim of the study is to check if participants achieve remission after treatment with the vedolizumab. Remission means symptoms improve or disappear and an endoscopy shows no signs of inflammation.
Participants will receive 3 infusions of vedolizumab over 6 weeks. Then, those who have a clinical response will receive either a high dose or low dose of vedolizumab once every 8 weeks. They will receive the same dose every time.