Increased risk of respiratory syncytial virus infection in patients with active inflammatory bowel disease: a matched cohort study

Abstract Background Immune dysregulation, immunosuppressive therapy and active inflammatory bowel disease (IBD) increase susceptibility to respiratory syncytial virus (RSV) infection. We evaluated the risk of RSV infection in patients with active and nonactive IBD. Methods Using the TriNetX Analytics Network from October 2024 through March 2025, we identified adult patients (aged ≥18 years) with IBD. Patients were classified as having active IBD if they had recent IBD complications, IBD-related surgery, or elevated inflammatory markers (within preceding 6 months); those without recent complications,surgeries, or elevated inflammatory markers were classified as having nonactive IBD within the same period. Outcomes were assessed within 180 days after the index date and included RSV infection, bacterial pneumonia, intensive care unit (ICU) admission, and mechanical ventilation. Results Among 141 763 patients (47 883 patients with active IBD, 93 880 patients with nonactive IBD), 2879 patients with active IBD and 3583 with nonactive IBD received the RSV vaccination. After matching, each cohort included 46 308 patients. Active IBD was associated with higher odds of RSV infection (adjusted odds ratio [aOR], 1.55; 95% CI, 1.18-2.04), bacterial pneumonia (aOR, 2.58; 95% CI, 2.08-3.19), ICU admissions (aOR, 2.07; 95% CI, 1.88-2.28), and mechanical ventilation (aOR, 2.41; 95% CI, 2.01-2.88). RSV risk remained higher among patients with active IBD both with and without systemic corticosteroid exposure. Among RSV-vaccinated patients, RSV infection rates were not significantly different between active and nonactive IBD (aOR, 1.26; 95% CI, 0.78-1.79). Conclusion Patients with active IBD had higher risk of RSV infection. Increased RSV risk was observed both among patients with active IBD with and without systemic corticosteroid exposure. Among RSV-vaccinated patients, RSV infection rates were not significantly different between active and nonactive IBD. Further prospective studies are needed to validate these findings.