(CNN) - United States researchers say they've successfully tested a vaccine for malaria.
More than three dozen volunteers received multiple doses of a vaccine produced with a weakened form of the disease.
Malaria, a mosquito-borne tropical disease, kills about one million people a year and sickens more than 200 million. Researchers found this vaccine protected most of the patients from getting malaria.
Although the results are promising, researchers say more extensive testing is required.
The findings were published in the journal Science.