Vaccination-Related Worsening of Disease in Patients with Immune-Mediated Inflammatory Diseases

OBJECTIVES: Vaccinations are important for patients with immune-mediated inflammatory diseases (IMID), including multiple sclerosis (MS), inflammatory rheumatic and musculoskeletal diseases (iRMD), or inflammatory bowel diseases (IBD). However, safety concerns persist regarding potential disease worsening. This study assessed the risk of IMID worsening requiring emergency hospitalization following pneumococcal or influenza vaccination. METHODS: In this retrospective population-based cohort study, six target trial emulations with time-dependent matching were performed using claims data from the German statutory health insurance BARMER from January 2013 to December 2019. Covariate-adjusted hazard ratios (HR) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. RESULTS: Of 432,768 IMID patients, 9,526 MS, 108,422 iRMD, and 19,238 IBD patients were included in pneumococcal trials, and 30,416 MS, 265,850 iRMD, and 53,056 IBD patients in influenza trials. No increased risk was found; instead, a trend towards risk reduction was observed. Pneumococcal trials showed HRs of 0.91 [95% CI 0.58-1.42] for MS, 0.60 [0.38-0.94] for iRMD, and 0.89 [0.62-1.26] for IBD. The influenza trials showed similar results (MS: 0.94 [0.73-1.21]; iRMD: 0.79 [0.63-1.00]; IBD: 0.83 [0.68-1.03]). CONCLUSIONS: No evidence of increased IMID worsening requiring emergency hospitalization after pneumococcal or influenza vaccination was found, supporting the safety of immunizing these patients.