Serological immunity against vaccine-preventable diseases in children with inflammatory bowel disease at diagnosis.

Objectives: Patients with inflammatory bowel disease (IBD) are at increased risk of vaccine-preventable diseases. However, vaccination coverage in this population is often suboptimal. This retrospective study assessed the vaccination status and vaccine serology of children diagnosed with IBD in a high-income country with broad vaccine access. Methods: Medical records of children under 16 years diagnosed with IBD between 2009 and 2023 were retrospectively reviewed. Demographic and clinical data, vaccine history, and vaccine serology, at the time of diagnosis, were analyzed. Results: A total of 42 IBD patients were included, with a median age at diagnosis of 11 years. Vaccine records were available for 31 (74%), of whom only 6 (19%) had up-to-date vaccinations. Vaccine serology did not always correlate with vaccine history. Most patients had the required doses for age for tetanus, diphtheria, Conclusions: This study reveals major gaps in vaccination coverage and seroprotection among children with IBD. Pneumococcal and Hepatitis A/B vaccines should be given at diagnosis, and measles and varicella serology should be assessed to enable timely catch-up with live vaccines before immunosuppression.