Induction of Immunity Against Streptococcus Pneumoniae in Adults With Inflammatory Bowel Disease

Patients with inflammatory bowel disease are at increased risk for infections due to their baseline disease and the subsequent immunocompromising regimen. Streptococcus pneumoniae (pneumococcus) has a high mortality and morbidity, particularly in immunosuppressed patients. A polysaccharide vaccine covering 23 different serotypes of pneumococcus (PPSV23) is currently recommended to immunocompromised patients to reduce their risk of invasive pneumococcal infections (such as bacteremia, meningitis, or pneumonia). Its immunogenicity is however limited, both in magnitude and duration, even in healthy individuals. Several studies have investigated the immunogenicity of PPSV23 in patients with IBD and have reported a marked inhibitory effect of immunosuppressive therapy on vaccine responses. A pneumococcal conjugated vaccine (PCV) was originally developed to protect young children and demonstrated as highly effective and safe. PCV13 contains polysaccharides from thirteen different serotypes, conjugated to an inactivated diphtheria toxin, and has the capacity to induce both primary and memory responses. PCV also appears much more immunogenic than PPSV23 in immunocompromised pediatric and adult patients. Whether some therapeutic regimens may nevertheless prevent the induction of protective responses by PCV13 is yet unknown. To date, no study has yet reported the immunogenicity / safety of PCV13 in adult IBD patients. Study's objectives * Primary objective: evaluate the immunogenicity and safety profile of PCV13 immunization in IBD patients * Secondary objective: evaluate the relative influence of treatment and disease on immune responses to PCV13 immunization * Tertiary objective: evaluate the immunity/vulnerability against vaccine-preventable diseases (VZV, measles) in the IBD cohort of Switzerland (optional, depending on funds)