Malaria due to Plasmodium falciparum remains a major cause of mortality and morbidity in tropical countries.

A novel new pre-erythrocytic vaccine (currently known as RTSS/ASO2) however has recently been developed and has undergone clinical trials in the Gambia. The vaccine is given in three doses on days 1 28 and 150. The Gambia trial was randomised with 132 adult males being given the full course of malaria vaccine and a control group of 125 receiving a similar course of rabies vaccine. The trial was blinded to both patients and investigators and the vaccination programme was completed before the start of the season of maximal malarial transmission. Trial participants were closely followed for 15 weeks with regular clinical surveillance as well as with malarial blood slides. At the end of this period a subgroup were given a fourth booster vaccination and followed during the following years malarial season. The vaccine was well tolerated with no significant adverse effects. (excerpt)