Since immunomodulators and antitumor necrosis factor (TNF) agents are increasingly used to treat inflammatory bowel disease (IBD), it is recommended to administer antipneumococcal vaccination to prevent opportunistic pneumonia. There is some evidence that concomitant immunosuppression may impair the immune response to vaccination. We aimed to evaluate the response rates to pneumococcal vaccination in four different treatment groups (mesalamine, azathioprine, infliximab, infliximab plus azathioprine).

In all, 96 patients with IBD (54 with Crohn's disease; 42 with ulcerative colitis) were administered a 23-valent polysaccharide pneumococcal vaccine (PSV-23). The levels of antipneumococcal antibodies were measured prior to and at least 3 weeks after vaccination. Response rates and risk factors for impaired immunosuppression were investigated. Patients on mesalamine were used as a control group.

Patients administered infliximab or the combination immunosuppressive therapy had significantly lower response rates to vaccination (57.6% and 62.5%, respectively) compared with the group on mesalamine (88.6%; P < 0.05 for both comparisons). Azathioprine alone did not influence the response rate to vaccination (78.9%; P = 0.43 vs. mesalamine group). Mean antibody titers after vaccination were significantly lower in patients under infliximab or combined immunosuppression than controls (P < 0.05). Immunosuppression with infliximab or combination therapy significantly decreased the likelihood of responding to vaccination (odds ratio [OR] = 0.17, 95% confidence interval [CI] 0.04–0.64, P = 0.009, and OR = 0.21, 95% CI 0.05–0.91, P = 0.038, respectively). Pneumococcal vaccination was generally safe and well tolerated.

Anti-TNF therapy alone or in combination with azathioprine impairs the response to pneumococcal vaccination in patients with IBD. All patients with IBD should therefore be vaccinated before starting anti-TNF therapy.