[Meningococcal vaccination: which one? When? Why?].

Two kinds of meningococcal vaccines are available for invasive meningococcal infections (IMI) prevention, non conjugated polysaccharide vaccines anti A+C or anti A+C+W135+Y and conjugated polysaccharide vaccines anti-C. The last one have the advantage of being effective from 2 months of age. Vaccination should to be used in four circumstances: for subjects remaining in close contact with an IMI case; for pilgrims going to Mecca (A+C+W135+Y vaccine must be used); for travelers to a location with active transmission of IMI and close contacts with local population; in case of "mass" vaccination decided by health authorities. Generalised vaccination of all of one or more age groups has been done for serotype C in some European countries, because of high incidence. Effectiveness of this kind of intervention should be weighted with the risk of immunoselection of another serotype and with the possibility of a spontaneous decrease of the incidence.