Inclusion Criteria:  • Male or female subjects who are more than 18 years of age, on the day of signing informed consent.  Patient affiliated to the health insurance system. Documented diagnosis of CD or UC established based on standard clinical, endoscopic, and histological criteria. CD or UC remission defined per clinical assessment as a Harvey Bradshaw Index (HBI) score ≤4 for CD patients and a Partial Mayo Score (PMS) ≤2 with each sub-score of 1 or less for UC and/or according to ECCO classification within previous 6 months. Currently treated with IV infliximab: originator or biosimilars. Patients agreeing to switch from IV to SC formulation or who have already switched since maximum 3 months. Receiving or not the concomitant following drugs (but must remain on stable dose for 12 weeks): Oral 5-aminosalicylates (5ASA) compounds or rectal formulations of 5ASA provided the dose to be stable at least 4 weeks before switching.  Azathioprine, 6-MP or methotrexate provided the dose has been stable for 4 weeks prior to inclusion (dose must remain stable for 10 weeks after switching).  Each patient is required to provide written informed consent to be included in the study.  Exclusion Criteria:  Current use of vedolizumab or ustekinumab Current use of JAK inhibitors or S1P modulators Current use of steroids or within the last three months for IBD Treatment with any investigational agent in the past 30 days or five half-lives prior to the inclusion visit Current CD abscess Active clinically significant infection or HIV, Hep B, Hep C, untreated tuberculosis Female subjects with pregnancy or breastfeeding