The relationship between Zoster serology, vaccination uptake and infection rates: a single-centre cross-sectional study.

Objective: This study aimed to assess the prevalence of Varicella-Zoster Virus (VZV) immunity, vaccination uptake and incidence of VZV-related events in inflammatory arthritis (IA) patients initiating biologic or targeted synthetic disease-modifying antirheumatic drugs.

Methods: An observational study was conducted in a single hospital between March 2019 and December 2020. Ninety-three IA patients were included. Data were collected from electronic health records and analysed using the chi-squared test.

Results: The majority of patients (91.4%) were seropositive for VZV, reaffirming the necessity for vaccination. In total, 8.6% of the cohort received the Zostavax vaccine, despite a small yet significant number of patients (4.3%) experiencing Herpes Zoster after initiating treatment. Multiple factors contributed to low vaccine uptake, including limited vaccine availability, discrepancies between the British Society for Rheumatology and Joint Committee on Vaccination and Immunisation guidelines, vaccine hesitancy and concerns regarding vaccine efficacy and risks.

Discussion: Significant VZV immunity exists among patients prior to targeted therapy commencement. Risk factors for VZV-related events include Janus kinase inhibition, increasing age and long-term steroid use. VZV-related events occurred exclusively in patients with prior viral immunity. Despite most patients having serological evidence of prior VZV exposure, our study exposes critical gaps between current clinical guidelines and practice, particularly in VZV vaccine uptake. Barriers to vaccination include inconsistent guidelines, limited vaccine availability and patient-level hesitancy. This is concerning as our cohort demonstrated small but significant rates of zoster, mostly among patients on long-term steroids.