P537 Prevalence of post-COVID-19 vaccination IBD flare-ups: a single-center prospective study.

Roblin, X.(1)*;Williet, N.(2);Faure, J.(3);Bastide, L.(2);Barrau, M.(2);Paul, S.(4);

(1)CHU Saint Etienne - Hospital Nord, Department of Gastroenterology and Hepatology- Inserm- CIC1408, Saint Priest en Jarez, France;(2)CHU saint etienne, Gastroenterology, Saint etienne, France;(3)CHU Saint etienne, Gastroenterology, Saint etienne, France;(4)CHU Saint Etienne, Immunology, Saint Etiennne, France;



Case reports of IBD flares after COVID-19 vaccination have been reported. These cases appear to be rare. In a recent study analyzing adverse event rates and impact on clinical activity of IBD after COVID-19 vaccination, the authors reported a rate of IBD reactivation in 2% of cases defined as reactivation of symptoms associated with a change in therapy (Prevent COVID Study) (Weaver et al. IBD 2022).


Any patient with IBD, followed as an outpatient in our department and having accepted to be vaccinated against COVID-19, was proposed this study. All the patients included in the study had to contact the department if, within one month of receiving the COVID-19 vaccine, they presented a clinical picture suggestive of an IBD relapse. The patients were reviewed in emergency and an assessment of IBD activity was made: clinical activity score, CRP and/or calprotectin dosage, short endoscopy in case of UC, colonoscopy or MRI in case of CD.  The link between vaccine and relapse was defined by the absence of clinical activity for at least 3 months before vaccination and relapse of the disease at the latest within 30 days after vaccination without therapeutic modification in between.



231 patients (mean age: 44.6 years, sex ratio M/F=1.1, 43.3% MC) were eligible. 176 patients had at least three doses of vaccine, all with mRNA, and 55 with no more than two doses. 97 patients (42%) were infected at least once with COVID 19, confirmed by PCR after at least one dose of vaccine, all without resorting to hospitalization, resuscitation or death. 29 patients (12.5%) developed IBD after vaccination (43.6% MC, sex ratio=1, 80% of cases after 3 doses of vaccine) after a median time of 8.5 days (5-17 days). Patient characteristics, treatment received, number of vaccinations, or Covid infection were comparable between groups with and without reactivation after COVID-19 vaccine (P=NS).  The risk of relapse after vaccination was 29 per 646 vaccine doses (4.4%). Table 1 reports pre-exacerbation treatments and proposed treatment changes as well as medium-term response. For IBD flares, no severe forms, hospitalization or surgery were observed. Fifteen patients were optimized on their treatment and 18 were switched to another treatment. All were put into clinical remission of their disease. In univariate analysis, no clinical parameter (type of IBD, age, sex, smoking), the number of previous vaccinations, a previous infection with covid 19 or the type of treatment was associated with a significant risk of relapse after vaccination.


The risk of IBD relapse in patients in durable clinical remission is possible after COVID-19 mRNA vaccination but remains low (4%). No risk factors were isolated in this work.