Results of a stage three trial after 18 months of follow up show that RTS,S almost halved the number of malaria cases in young children (aged 5-17 months at first vaccination) and reduced by around a quarter the malaria cases in infants (aged 6-12 weeks at first vaccination). Eleven African research centres in seven African countries are conducting this trial, together with GlaxoSmithKline (GSK) and the PATH Malaria Vaccine Initiative (MVI), with grant funding from the Bill & Melinda Gates Foundation to Malaria Vaccine Initiative (MVI).