Researchers reported on Monday that a revolutionary vaccine against malaria protected up to 65 percent of infants from infection in two studies in Africa. The studies, published online today in the New England Journal of Medicine, were reported at a New Orleans meeting of tropical medicine researchers and were hailed as a significant breakthrough in the fight against one of the most persistent infectious diseases.

It is the first malaria vaccine to make it this far, and if further studies are successful, marketing approval could be sought as early as 2011. The vaccine was developed by the British-based GlaxoSmithKline PLC and it is called RTS,S.

In the first study, conducted in Kenya and Tanzania, 894 children ages 5 months to 17 months were innoculated either with the three-dose experimental malaria vaccine or a rabies vaccine as a control group. In the eight-month follow-up period, researchers found that children receiving RTS,S had 53% fewer diagnosed cases of malaria (38 episodes compared with 86 among recipients of the control rabies vaccine).

In the other study, conducted in Tanzania, the vaccine was given to 340 infants at 8, 12 and 16 weeks of age, along with vaccines against polio, diphtheria, tetanus, pertussis (whooping cough) and Haemophilus influenzae B without lessening the safety or effectiveness of any of the vaccines.

"Even a partially effective vaccine has the potential to save hundreds of thousands of lives each year," said Christian Loucq, director of the nonprofit PATH Malaria Vaccine Initiative, which helped to conduct the study.