Meningitis due to Neisseria meningitidis serogroup A represents an important public health problem in sub-Saharan Africa. New meningitis vaccines (against pneumococci, Hemophilus influenzae and serogroup C meningococci) manufactured by conjugating the pol ysaccharide to a carrier protein have been shown to not only prevent disease of the vaccinated individuals but also to prevent carriage; thus having a strong herd effect. This project aims to investigate the ability of a new and affordable serogroup A meningococcal vaccine (MenAfriVac) to reduce the carriage prevalence of serogroup A meningococci as a reflection of herd immunity. Burkina Faso is the first country to introduce the vaccine and a mass vaccination of the population aged 1-29 is planned fo r the end of 2009. Sampling campaigns of thousands of volunteers in three health districs in Burkina Faso will be done before and after the introduction of the vaccine.With the support of the Research Council of Norway and the other partners, the projec t started in 2008 and is progressing well. Sampling campaigns have been conducted in three health districts in Burkina Faso according to the study protocol. However, preliminary data show that the carriage prevalence of serogroup A meningococci is lower t han expected. Due to technical problems (poor quality of commercial agar plates), the first sampling campaign might need to be excluded. In addition, due to delay in vaccine introduction extra sampling campaigns have to be performed in order to obtain a s ampling size allowing statistically significant results.This application also aims to support the organization and the participation of scientists from Burkina Faso and Norway involved in the carriage study in an important workshop that will be held in India, where MenAfriVac is manufactured.