Serologic immunogenicity and safety of herpes zoster subunit vaccine in patients with rheumatoid arthritis receiving Janus kinase inhibitors

Objective Patients with RA treated with Janus kinase inhibitors (JAKis) are at increased risk of herpes zoster (HZ). The objective of this study was to investigate the serological immunogenicity and safety of the HZ subunit (HZ/su) vaccine in RA patients treated with JAKi, for which little is known. Methods RA patients treated with JAKi (n=82) at the Department of Rheumatology, Skane University Hospital, Lund and Malmo, Sweden, and healthy controls (n=51) received two doses of the HZ/su vaccine (Shingrix). Vaccine-specific antibody responses were analysed using indirect ELISA. Post-vaccination antibody levels were compared between patients and controls using analysis of covariance. Potential predictors for vaccine response were investigated using a multivariable linear regression analysis. Self-reported adverse events (AEs) and changes in RA disease activity were analysed. Results Following vaccination, vaccine-specific antibody levels increased significantly in both patients and controls (P<0.0001). A total of 80.5% of patients and 98.0% of controls achieved a <greater than or equal to>4-fold increase in antibody levels. Post-vaccination antibody levels were lower in patients than controls [ratio 0.44 (95% CI 0.31, 0.63)] and lower in patients receiving JAKi+methotrexate than JAKi monotherapy [ratio 0.43 (95% CI 0.24, 0.79)]. AEs, mostly mild/moderate, were common. One patient developed HZ and six patients (6.5%) had increased RA disease activity following vaccination. Conclusion The HZ/su vaccine was serologically immunogenic in most RA patients treated with JAKi. Moreover, the vaccine had an acceptable safety profile. These results support recommendations for use of the HZ/su vaccine in this vulnerable population. Trial registration ClinicalTrials.gov (https://clinicaltrials.gov), NCT03886038.