Meningococcal conjugate vaccines have been developed by linking a capsular polysaccharide to a carrier protein. Conjugate vaccines are immunogenic in very young children and they prevent carriage. A serogroup C meningococcal conjugate vaccine has been deployed successfully in the UK and in other European countries with a dramatic reduction in the incidence of serogroup C disease and a marked drop in the prevalence of serogroup C meningococcal carriage.
Development of a serogroup A meningococcal conjugate vaccine for use in Africa has been slow. However, in 2001, the Meningitis Vaccine Project (MVP), a partnership between WHO and PATH, was created with support from the Bill and Melinda Gates Foundation to do this. MVP’s goal was to develop a low-cost, monovalent serogroup A conjugate vaccine which can be used for mass immunisation programmes in countries of the African meningitis belt and also for immunisation of infants
MVP has succeeded in developing such a vaccine, PsA-TT (MenAfriVac). MenAfriVac induces a superior immunological response to that of the serogroup A polysaccharide vaccine and also induces immunological memory. Following clinical trials in Africa and India, the vaccine was licensed in India in 2009 and prequalified by WHO in 2010. Starting in 2010, MenAfriVac is being rolled out across the African Meningitis belt. By December 2012, the vaccine had been introduced into 10 countries, and 100 million individuals had been immunised.