Real-World Safety and Herpes Zoster Outcomes After Recombinant Zoster Vaccination in Inflammatory Bowel Disease

Background/Objectives: Patients with inflammatory bowel disease (IBD) are at an increased risk of herpes zoster (HZ), particularly during immunosuppressive treatment. To assess the safety of the recombinant zoster vaccine (RZV, Shingrix^®) and describe HZ occurrence in a real-world IBD cohort, including patients receiving advanced therapies. Methods: This prospective, single-centre observational study included 114 adults with IBD who were offered RZV; 69 received at least one dose, and 45 declined or postponed vaccination. Follow-up began at the vaccine proposal. For time-to-event analyses, vaccination was modelled as a time-varying exposure beginning 14 days after a documented second dose. IBD clinical relapse was defined by worsening disease-activity indices and/or treatment escalation. Results: During a median follow-up of 17 months (IQR 9-29), 11 patient-reported HZ episodes occurred: 8/69 (11.6%) among patients who received vaccination and 3/45 (6.7%) among those who did not. The time-dependent association between complete vaccination and HZ was not statistically significant (HR 2.51; 95% CI 0.66-9.51; p = 0.18), and adjustment for advanced therapy did not materially change the estimate. Prior HZ was associated with a higher risk of a subsequent reported episode (adjusted HR 6.26; 95% CI 1.80-21.76; p = 0.004). IBD clinical relapse occurred in 4/69 (5.8%) vaccinated and 2/45 (4.4%) unvaccinated patients (p = 1.00). Among 72 patients receiving advanced therapy, HZ occurred in 4/42 vaccinated and 2/30 unvaccinated patients (p = 1.00), while IBD relapse occurred in 3/42 and 1/30, respectively (p = 0.64). No serious vaccine-related adverse events or significant pre-/post-vaccination changes in disease activity were observed. Conclusions: RZV showed a favourable short-term safety profile in patients with IBD, including those receiving advanced therapies. The small number of self-reported HZ events and the non-randomised design preclude conclusions regarding vaccine effectiveness.