It has been called a major advancement in malaria prevention -- the world's first malaria vaccine that can cut a child's risk of contracting malaria in half.
Researchers say the initial results of their study show the vaccine to be 50 percent effective in young children.
The experimental drug is in the final stages of testing in Africa. The drug's developers have called their new findings a milestone.
The vaccine won't be available for at least three years as further testing still needs to be done to find out how long the protection lasts.
Then the vaccine would be reviewed by government agencies in Europe and Africa.
"We still have a way to go," Tsiri Agbenyega, lead researcher for the African study, said in a conference call with reporters.
Malaria kills nearly a million people around the world annually. More than 90 percent of them live in Africa. Victims most often include young children and pregnant women.
The new vaccine targets a malaria parasite found in sub-Saharan Africa. Malaria spreads through mosquitoes, which bite people and flush malaria parasites into the bloodstream.
The new study began in 2009 and involves more than 15,000 children in Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique, and Tanzania.
Early results of the study were released Tuesday at a malaria conference in Seattle, Wash., and were published by the New England Journal of Medicine.