Impact of a new and affordable conjugate meningococcal vaccine on carriage of serogroup A Neisseria meningitidis and disease transmission

Meningococcal meningitis is causing repeated massive epidemics in an area south of Sahara, termed the meningitis belt. The disease-causing bacteria are mainly serogroup A meningococci. These are transmitted between individuals by air-borne droplets and as ymptomatic carriers are the principal source of spread of the organism in the population. New meningitis vaccines (against pneumococci, Hemophilus influenzae and serogroup C meningococci) manufactured by conjugating the polysaccharide to a carrier protein have been shown to not only prevent disease of the vaccinated individuals but also prevent carriage; thus having a strong herd effect. This project aims to test the ability of a new and affordable serogroup A meningococcal conjugate vaccine (MenAfriVac) , developed by a public-private partnership between the World Health Organization (WHO) and the Program for Appropriate Technology in Health (PATH), to reduce the carriage prevalence of serogroup A meningococci, since this is indicating an ability to indu ce a herd effect in the population. The pilot introduction of the vaccine will be in Burkina Faso in November 2008, and the project will therefore collect data on carriage prevalence at several time-points prior and post the vaccine introduction. As the c arriage prevalence of the serogroup A meningococcus is expected to be low, about 4,500 individuals will be sampled at each time-point to assure statistical power. The strains will be characterized by molecular methods and compared to the disease-causing s trains in Burkina Faso. The effect of the vaccine on salivary antibodies will be tested on a subset of the population. The project will contribute to capacity building of the microbiological laboratories, to enhance epidemiological surveillance and reinfo rce the network of partners in the fight against meningococcal meningitis.