Patients with inflammatory bowel disease (IBD) are predisposed to pneumococcal infections due to their underlying disease and iatrogenic immunosuppression. Vaccination with the 13-valent pneumococcal conjugated vaccine (PCV13) is recommended, but with poor take-up and few data available. We performed an open-label, phase IV, multicenter study to evaluate the safety and immunogenicity of PCV13 in adults with IBD and to analyze the influence of immunomodulating treatments on anti-pneumococcal seroresponses.