Immunogenicity and Safety of Recombinant Herpes Zoster Vaccine in Patients with Inflammatory Bowel Disease on Vedolizumab or Anti-TNF therapy

Background: Patients with inflammatory bowel disease (IBD) are at increased risk of herpes zoster (HZ) and should receive the recombinant herpes zoster vaccine (RZV). We sought to assess the immunogenicity and safety of RZV series in patients receiving anti-tumor necrosis factor (TNF) therapy compared to those receiving vedolizumab. Methods: This single-center prospective study enrolled patients with IBD on vedolizumab or anti-TNF monotherapy receiving RZV. Primary outcome assessed cell-mediated immunity (CMI) differences between groups post-vaccination. Secondary outcomes included humoral response, sustained immunity, and safety monitoring for adverse events and IBD flares. Assessments occurred at baseline, 30, 240, and 425 days post-vaccination. Statistical analyses included non-parametric Mann-Whitney U tests for between-group comparisons and Wilcoxon signed-rank tests for within-group changes, with significance set at p<0.05. Results: Thirty-three patients enrolled (16 vedolizumab, 17 anti-TNF). CMI responses increased post-vaccination in both groups (median 56 cells/million IQR 21-102 vs 33 cells/million IQR 11-73; p=0.13), with no significant difference between treatment groups. Both groups showed strong antibody responses to vaccination (pre-immunization median: 349.9 mIU/ml IQR 276.8-402.5 vs. 90-day median: 605.0 mIU/ml IQR 525.6-641.0; p<0.001). CMI responses remained elevated at both day 240 and 425 assessments. Antibody levels remained elevated through day 425 (549.1 mIU/ml, IQR 516.1-585.6), substantially higher than pre-vaccination levels. No IBD flares occurred; most adverse events were mild and transient. Conclusions: RZV demonstrated robust immunogenicity and favorable safety profile in IBD patients receiving either vedolizumab or anti-TNF therapy. Both cellular and humoral immune responses persisted through 425 days post-vaccination.