Malaria Vaccine: Modest, Short-Term Protection in Semi-Immunes

Malaria parasites are becoming resistant to more drugs, lending urgency to the quest for new tools, including vaccines. Researchers tested a pre-erythrocytic malaria vaccine, RTS,S/AS02 -- based on the circumsporozoite protein of Plasmodium falciparum -- in men in The Gambia, where malaria transmission is seasonal. The primary endpoint was time until the first malaria infection. In the trial, which had partial support from the manufacturer and was timed to coincide with the period of most intense malaria transmission, volunteers from 6 villages were randomized to receive 3 intramuscular doses of malaria vaccine or human rabies diploid vaccine on days 0, 28, and 150. Before vaccination, participants were treated with sulfadoxine/pyrimethamin…