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P201. Effect of immunosuppression on immune response to pneumococcal vaccine in inflammatory bowel disease: A prospective study

G. Fiorino1,2, P. Naccarato1, H. Szabò1, O. Sociale1, S. Vetrano1, A. Repici3, L. Peyrin-Biroulet4, A. Malesci5,6, S. Danese1

1IRCCS Humanitas – IBD Unit, Rozzano, Italy; 2University of Messina, Messina, Italy; 3IRCCS Humanitas – Endoscopy Unit, Rozzano, Italy; 4Inserm U954 and Department of Hepato-Gastroenterology, University Hospital of Nancy, Vandoeuvre-lès-Nancy, France; 5IRCCS Humanitas – Gastroenterology, Rozzano, Italy; 6University of Milan, Milan, Italy

Aim: Immunomodulators and anti-TNF agents are increasingly used in the treatment of inflammatory bowel disease (IBD). Anti pneumococcal vaccination is recommended to prevent opportunistic pneumonia in course of pharmacological immunosuppression. There is limited evidence that concomitant immunosuppression can impair response to vaccination. Aim of the study was to evaluate the response rates to pneumococcal vaccination and the impact of IBD-related medications (azathioprine and/or infliximab).

Materials and Methods: 96 consecutive patients with IBD (54 CD; 42 UC) were administered 23-valent polysaccharide vaccine (23-PSV). Blood samples to detect anti-pneumococcal antibodies levels were collected before and at least 3 weeks after vaccination (mean interval 8 weeks, range 3–35) and antibodies titles were measured by ELISA. Response to vaccination was defined as two-fold increase of antibody titles compared to baseline. Response rate to vaccination and risk factors of impaired immunosuppression were investigated considering age, sex, baseline anti-pneumococcal antibodies and immunosuppression and using logistic regression and Fisher's exact test. Patients on mesalamine were considered as control group.

Results: Patients under infliximab or combined immunosuppression had significant lower response to vaccination (respectively 57.6% and 62.5%, p < 0.05, Fig. 1) compared to mesalamine group (88.6%). Patients with azathioprine did not show significantly lower response rate (78.9%, p = 0.34). Sex, age, baseline antibody titres did not affect the response to vaccination. Immunosuppressed patients were more likely not to respond to vaccination compared to controls (OR 4.06, p < 0.05). Immunosuppression with infliximab or combination therapy significantly increased the probability not to respond to vaccination (OR 12.1 and 25.5 respectively, p < 0.05).

Conclusion: Anti-TNF therapy alone or in combination with azathioprine impairs response to pneumococcal vaccination in IBD patients. All IBD patients should be vaccinated at least three weeks before starting with anti-TNF therapy.

1. Melmed GY, Agarwal N, Frenck RW, et al. Immunosuppression impairs response to pneumococcal polysaccharide vaccination in patients with inflammatory bowel disease. Am J Gastroenterol. 2010;105(1):148–54.

2. Rahier JF, B.-H.S., Chowers Y, Conlon C, et al. on behalf of the European Crohn's and Colitis Organisation (ECCO), European evidence-based Consensus on the prevention, diagnosis and management of opportunistic infections in inflammatory bowel disease. Journal Crohn's Colitis, 2009;3(2):47–91.

Figure 1. Response rates to vaccination.