Vaccine Prevention of Meningococcal Disease: Making Slow Progress

All is not well in the fight against menin-gococcal disease. Despite the availability, for decades, of meningococcal vaccines, Neisseria meningitidis remains a leading cause of meningitis, sepsis, and other serious infections in both industrialized nations and the developing world [1]. The meningitis belt in sub-Saharan Africa continues to suffer from devastating epidemics of infection due to serogroup A. Unexpectedly , a serogroup W-135 strain has also recently emerged as a cause of epidemic disease in that region, potentially complicating vaccine development and prevention efforts. There are no vaccines for sporadic serogroup B infection because of immunologic cross-reactivity of B poly-saccharide with human neural tissue and other related factors. This is truly a vexing problem, because serogroup B strains account for a substantial proportion of me-ningococcal disease in Europe, the Amer-icas, and elsewhere, and these strains predominate among infants—the group that has both the highest risk of menin-gococcal disease and the least immuno-logic maturity. Although a new tetravalent conjugate vaccine was recently licensed in the United States, initial licensure was limited to individuals aged 11–55 years; no licensed product is yet available for the children who are at the highest risk. Clearly, we have a long way to go in preventing meningococcal disease; progress has been slow [2]. With that somewhat pessimistic back-drop, substantial progress is being made in the development and licensure of new meningococcal vaccines. Work is being done to develop a safe, effective, and affordable serogroup A conjugate vaccine for use in the meningitis belt [3]. Tailor-made serogroup B vaccines have been used to control long-standing epidemics (most recently in New Zealand [4]), which are generally clonal and are, therefore, more amenable to vaccine prevention. In addition , there has been progress made towards identifying novel antigens that could potentially be effective against the very diverse group of strains that cause endemic serogroup B disease [5]. Finally, new conjugate vaccines are becoming available, including a serogroup A/C/W-135/Y conjugate vaccine that was licensed in the United States in 2005 and in Canada in 2006 and is now recommended by the Advisory Committee on Immunization Practices for routine use in adolescents in the United States [6]. This represents the first time that a meningococcal vaccine has been recommended for routine use in the general US population. It is likely that conjugate vaccines will be available for younger children and infants in the United States in the next few years. The …