Meningococcal conjugate vaccines.

Disease caused by Neisseria meningitidis is associated with high mortality rates and significant sequelae. Polysaccharide meningococcal vaccines have been available for > 20 years, and have been used in travellers to control outbreaks, and in some countries for adolescents entering college, although they provide only a short duration of immunity and do not produce a herd effect. Monovalent and quadrivalent (A, C, Y, W-135) meningococcal conjugate vaccines have recently been licensed and endorsed for use in infants, children, adolescents and adults in various countries. Among the key features of the new meningococcal conjugate vaccines are stimulation of both B cell-dependent and T cell-dependent immune responses, induction of immunological memory and booster effects, longer-term protection, reduction of nasopharyngeal carriage of N. meningitidis, and herd immunity. Large, randomised, double-blind studies in adults, adolescents, children and infants have demonstrated the immunogenicity and safety of the new meningococcal conjugate vaccine formulations.