Navy Capt. Judith Epstein, director of the malaria program at the Naval Medical Research Center, has been searching for a malaria vaccine and may be on the verge of finding it. The NMRC, in collaboration with the NIH, Walter Reed Army Institute of Research and private firm Sanaria, recently tested a vaccine developed from a weakened strain of Plasmodium vivax, the most deadly form of malaria, on 40 human subjects. The vaccine had a 100% success rate in preventing malaria after the subjects were exposed to malaria-infected mosquitoes. More studies are needed, and Epstein estimates that a commercial vaccine is at least four years away.