COVID-19 and the impact of vaccination on the disease morbidity of Polish paediatric patients with inflammatory bowel disease.

Aim: We evaluated the frequency and severity of COVID-19, and vaccination status, in children with different forms of inflammatory bowel disease (IBD).

Methods: This was a prospective, observational cohort study that used a questionnaire to gather data on the patients' vaccination doses, medication and disease activity. Disease flare was defined as worsening IBD symptoms and changes in medication. Outcomes were stratified by vaccine type and medication classes.

Results: The questionnaire was completed by 320 children with IBD, and their parents or carers: 52.8% had Crohn disease, 46.9% had ulcerative colitis and 0.3% were unclassified. Just over a third (35.6%) had COVID-19, which was mild in 69.3%, moderate in 27.2% and severe in 3.5%. We found that 127 patients received at least one vaccine dose, but 23 patients were vaccinated after they had COVID-19 and were classified as unvaccinated. This meant that 104 vaccinated patients and 216 unvaccinated patients were studied. A fifth (20.2%) of the vaccinated children developed COVID-19, compared to 43.1% of the unvaccinated children.

Conclusion: Vaccination status had no statistically significant impact on the severity of COVID-19. Morbidity rates were similar between patients with Crohn disease and ulcerative colitis.