# Incidence of Severe COVID-19 Outcomes and Immunization Rates in Apulian Individuals with Inflammatory Bowel Disease: A Retrospective Cohort Study

## TL;DR

This study found that IBD patients in Apulia are not at higher risk of severe COVID-19 outcomes than the general population, and vaccination is key to reducing hospitalization and death.

## Contribution

The study provides regional evidence on the relationship between IBD, immunization, and severe COVID-19 outcomes in a matched cohort.

## Key findings

- IBD patients had similar rates of COVID-19 incidence, hospitalization, and lethality as the general population.
- Vaccination significantly reduced hospitalization and death risks in both IBD patients and controls.
- Age and male sex were identified as risk factors for severe outcomes, while vaccination coverage was high in both groups.

## Abstract

The etiology of Inflammatory Bowel Disease (IBD) is not fully understood but is believed to involve a dysregulated immune response to intestinal microbiota in genetically susceptible individuals. Individuals with IBD are at increased risk of infections due to immunosuppressive treatments, comorbidities, and advanced age. Current evidence indicates that IBD patients are not at higher risk of SARS-CoV-2 infection compared to the general population, though the risk of severe outcomes remains debated. A retrospective observational study was conducted using Apulian regional health data from 2020 to 2022. This study included 1029 IBD patients and 3075 controls, matched by age and sex. COVID-19 incidence, hospitalization, and case fatality rates were analyzed alongside vaccination coverage. No significant differences in COVID-19 incidence (IRR = 0.97), hospitalization (p = 0.218), or lethality (p = 0.271) were evidenced between IBD patients and the general population. Vaccination rates were high in both groups, with slightly higher uptake in IBD patients. Multivariate analysis identified age and male sex as risk factors for severe COVID-19 outcomes, while vaccination significantly reduced hospitalization and lethality risks. IBD patients in Apulia do not have an increased risk of COVID-19 infection or severe outcomes compared to the general population. Vaccination is crucial in protecting IBD patients, and ongoing efforts to promote vaccination within this population are essential. Future research should focus on the impact of specific IBD treatments on COVID-19 outcomes and the long-term effectiveness of vaccines.