Global epidemiology of meningococcal disease and vaccine efficacy.
BACKGROUND: Control of meningococcal infection has a high priority in many industrialized nations, because of the high mortality rates associated with invasive infection, the public health effects of disease outbreaks, and the position of Neisseria meningitidis as a leading infectious cause of death in childhood. Throughout the past 200 years, epidemics of meningococcal infection have been noted in Europe, Africa, Asia, the United States, and New Zealand. The proportions of cases caused by the 5 predominant capsular types (A, B, C, Y, and W135) associated with the disease vary among different regions and within specific geographic areas with time. Comprehensive disease control can be achieved only with the use of vaccines that target all of these disease-causing serogroups. METHODS: Routine immunization with a new generation of conjugate vaccines against serogroup C meningococci in the United Kingdom since 1999 has had a major effect on serogroup C disease in the region. The success of the vaccine involves 2 mechanisms, ie, (1) direct protective effects for vaccinated individuals through induction of bactericidal antibodies and (2) reductions in nasopharyngeal carriage of the organism and consequent generation of herd immunity through reductions in transmission to unimmunized individuals. CONCLUSIONS: Ongoing development of tetravalent A, C, Y, and W135 conjugate vaccines raises the hope that disease caused by these serogroups can be controlled in the near future. However, development of effective strategies to control serogroup B meningococcal disease is still needed for comprehensive control of meningococcal disease.