This is a multicenter, prospective, randomized, open study comparing two anti-pneumococcal vaccination strategies in patients with Chronic Inflammatory Bowel Disease (CIBD) treated by immunosuppressants and/or biotherapies. At present such patients are poorly protected by anti-pneumococcal vaccination. In addition, vaccination efficacy in this type of patient is much weaker than in the general population. There are two types of anti-pneumococcal vaccines: firstly a polysaccharide, Pneumo23® (PSV-23®) vaccine and secondly a conjugate, Prevenar13® vaccine. New recommendations have just been issued by the HSCP advising immunocompromised patients to follow a vaccination plan combining one dose of Prevenar13® followed by one dose of PSV-23® after an interval of two months. In the case of young children infected with HIV, the recommendation is to multiply doses of Prevenar13® before the PSV-23® injection to improve vaccine efficacy in these immunocompromised patients.