0201: Real-World study of immunogenicity and safety of the adjuvant recombinant vaccine against varicella zoster virus in patients with immune-mediated inflammatory diseases treated with Janus Kinase Inhibitors in comparison with healthy individuals

Background/Purpose: Patients with immune-mediated inflammatory diseases (IMIDs) receiving Janus Kinase Inhibitors (JAKi) are at increased risk of herpes zoster reactivation. The adjuvanted recombinant zoster vaccine (HZ/su) was recently approved in Europe; however, IMID patients were not included in the pivotal clinical trials. This study presents the largest real-world analysis of the immunogenicity and safety of HZ/su in IMID patients, compared to healthy controls.

Methods: We conducted a prospective, multicenter cohort study in Madrid, Spain, between March 2022 and March 2025. Vaccine response was defined as a fourfold or greater increase in antibody titers at follow-up compared to pre-vaccination levels, in line with clinical trial criteria.

Results: A total of 93 IMID patients and 107 healthy controls were enrolled. The mean age was 54 ± 10 years in the patient group and 61.8 ± 1.5 years among controls. Previous herpes zoster reactivation was reported in 9% of participants. A humoral immune response was observed in 51.4% of healthy controls, compared to 30% of patients. Immunogenicity was not influenced by other factors, including concomitant treatment with methotrexate, prednisolone, or the treatment line. No serious adverse events or major disease flares were reported.

Conclusion: IMID patients receiving JAKi therapy showed a reduced immunogenic response to the HZ/su vaccine compared to healthy individuals, likely influenced by concurrent immunosuppression. The vaccine was well tolerated, with a very low rate of adverse events. These findings support a strong recommendation for HZ/su vaccination in this vulnerable patient population, and advocate for varicella zoster vaccination prior to starting JAKi treatment.