A new malaria vaccine recently tested in Kenya and Tanzania has halved the risk of developing the disease in children. The vaccine, known as RTS,S, was developed by GlaxoSmithKline and is designed to prevent the destructive lysis of red blood cells after the liver is infected by Plasmodium falciparum. This species is responsible for the highest mortality and morbidity among victims of malaria and is considered more virulent than other members of the genus. Prevention of malaria in populations living in endemic areas could lead to the control and possibly even the elimination of malaria in some regions.