RTS,S/AS01 is an injectable vaccine that provides partial protection against malaria in young children. Like vaccines generally, RTS,S aims to trigger the body’s own immune system to defend against disease, in this case, malaria caused by Plasmodium (P.) falciparum, the deadliest species of the malaria parasite globally and the most prevalent in Africa. Specifically, RTS,S is designed to prevent the malaria parasite from infecting, maturing, and multiplying in the liver, after which the parasite would normally re-enter the bloodstream and infect red blood cells, leading to disease symptoms.