[Quadrivalent conjugate vaccines against ACWY meningococcal disease]

Invasive meningococcal disease (IMD) is caused by 6 serogroups of the bacterium Neisseria meningitidis (A, B, C, W, X and Y). It is among the most serious vaccine preventable infectious diseases, characterized by a high case-fatality rate and risk of permanent sequelae. Worldwide, the incidence of IMD is generally low with differences among regions and age groups. The risk increases in overcrowded conditions or in case of travel to endemic areas. The first vaccines produced using polysaccharide capsular antigens have demonstrated a good protective efficacy, but of short lenght. The conjugation of antigens with proteins allowed to obtain a longlasting antibody response towards 4 serogroups: A, C, W, Y. Currently four ACWY quadrivalent conjugate vaccines are available, three of them approved in Europe, which have shown high immunogenicity and safety. In 2020 the MenACYW-TT vaccine conjugated to tetanus toxoid was approved in the USA and it is presently authorized in Europe for the immunization of individuals from 12 months of age. Clinical studies have demonstrated immunogenicity and safety on population samples belonging to different age groups and non-inferiority in comparing it with other vaccines already in use. The possibility of having an increasing number of safe, immunogenic and effective vaccines against IMD allows us to imagine a future without invasive meningococcal disease. It is therefore important to extend vaccination to an increasing number of subjects of different age groups and risk conditions.