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 (R)) 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.