The natural history of COVID-19 in vaccinated inflammatory bowel disease patients.

AIM: Assess the characteristics of break through COVID-19 in Inflammatory Bowel Disease (IBD) patients, despite complete vaccination. METHODS: Patients who reported a COVID-19 at least 3 weeks after complete vaccination were asked to answer an on-line anonymous questionnaire which included patient and disease characteristics, vaccination history, and the evolution of COVID-19. RESULTS: Among 3240 IBD patients who reported complete vaccination between 1st May 2021 and 30thJune 2022, 402 (12.4%) were infected by SARS Cov-2 [223 male, 216 Crohn's disease (CD), 186 Ulcerative Colitis (UC), mean (SD) age 42.3 (14.9) years, mean (SD) IBD duration 10.1 (9.7) years]. Three hundred and sixty-nine patients (91.8%) were infected once and 33 (8.2%) twice. The mean (SD) time between last vaccination and infection was 4.1 (1.6) months. Overall, 351 (87.3%) patients reported mild constitutional and/or respiratory symptoms, 34 (8.4%) were asymptomatic and only 17 patients (4.2%) required hospitalization. Of hospitalized patients, 2 UC patients died of COVID-19 pneumonia. The remaining hospitalized patients did not need high flow oxygen supply or ICU admission. CONCLUSIONS: A minority of completely vaccinated IBD patients developed COVID-19 which evolved with mild symptoms and a favorable outcome. These results reinforce the importance of vaccination especially in vulnerable populations.