Live-attenuated vaccination in patients with inflammatory bowel disease while continuing or after elective switch to vedolizumab

Background/Aims: Vedolizumab (VDZ) is a gut-selective agent with a favorable safety profile. We aimed to assess the feasibility of elective switch from other advanced therapies to VDZ and subsequent live-attenuated vaccination while continuing VDZ in patients with inflammatory bowel diseases (IBD). Methods: We measured antibody titers specific for measles, rubella, mumps, and varicella viruses in IBD patients under immunosuppressive therapy. Those with negative titers and without vaccination history were judged unimmunized. Patients were administered vaccines while continuing VDZ or switched to VDZ if receiving other advanced therapies and then administered vaccines. Co-primary outcomes were the rate of maintaining disease severity after vaccination and the rate without vaccine-induced infection. Results: Among 107 unimmunized patients, 37 agreed to receive live-attenuated vaccines while continuing VDZ (17 patients) or after switching to VDZ (20 patients). In the 20 patients who electively switched to VDZ, disease severity was maintained except for 1 patient who developed intestinal infection. After 54 weeks, 18 patients (90%) continued to receive VDZ, excluding 2 patients who reverted to their originally administered biologics. In all 37 patients administered live-attenuated vaccines under VDZ treatment, disease severity was maintained after vaccination. Antibody titers became positive or equivocal in 34 patients (91.9%). There were no cases of vaccine-induced infection during a median observation period of 121 weeks. Conclusions: While live-attenuated vaccines are contraindicated under immunosuppressive therapy, they may be safely administered while receiving VDZ immunotherapy. Switching from other advanced therapies to VDZ and subsequently receiving live-attenuated vaccines may be a safe alternative in unimmunized patients. (Intest Res, Published online )