[Meningococcal vaccines: from polysaccharide to conjugate vaccines].

Vaccines against the polysaccharide meningococcal capsule lead to the prevention of invasive meningococcal diseases due to serotypes A, C, Y, W135. Polysaccharide vaccines, according to their immunological characteristics, could be used only to protect during a risk period relatively short: travel in endemic areas, epidemics and index cases. The dramatic success of the implementation of meningococcal C conjugate vaccines in England, and in several European countries has opened new perspectives. Three ACYW135 conjugate vaccines are or will soon be available. Meningococcal conjugate vaccines may be used for the same indications than polysaccharides vaccines, but also for long term individual protection (both for patient at high risk or without risk factor) and in national immunization programs. They must replace polysaccharide vaccines notably because of the risk of immunologic hypo-responsiveness.