Researchers have been trying for years to develop a vaccine for malaria, the deadly, mosquito-borne illness that kills nearly a million people a year and sickens 250 million others for more than 70 years. It looks like that day is finally here, as two studies published this week in The New England Journal of Medicine announce the most promising experimental vaccine to date to protect infants and young children against the terrible disease.

This is good news for billions of people worldwide who are under threat from malaria. At most risk however are children in sub-Saharan Africa. Children are vulnerable to malaria even before birth, if their mothers, especially those expecting their first child, develop placental malaria during pregnancy. Placental malaria causes the birth of underdeveloped or low birthweight babies and the threat of severe anemia or death to the woman.

The risk of infection is high as people are continually infected by mosquitoes throughout their lives. The parasites get inside the body through blood where they live and reproduce, causing fever and sometimes deadly brain infections.

But the disease could soon be stopped thanks to the new vaccine which proved successful in early tests. This 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 with support from the PATH Malaria Vaccine Initiative, a global nonprofit consortium that works with pharmaceutical companies. Phase III clinical tests, the last stage before seeking regulatory approval, will begin next year.

The first study, conducted in Kenya and Tanzania by Dr. Ally Olutu of the KEMRI-Wellcome Trust Collaborative Research Center in Kenya and colleagues, involved 894 children ages 5 months to 17 months. They were inoculated either with the three-dose experimental malaria vaccine or a rabies vaccine as a control group. After eight months, researchers found that children given RTS,S had 53 percent fewer diagnosed cases of malaria – 38 episodes compared with 86 among babies in the control group.

In the second study, conducted by Dr. Salim Abdulla of the Bagamoyo Research and Training Center in Tanzania and colleagues, the vaccine was given to 340 infants at 8, 12 and 16 weeks old along with vaccines against polio, diphtheria, tetanus, pertussis (whooping cough) and Haemophilus influenzae B without lessening the safety or effectiveness of the vaccines. This time, researchers found that infants given the malaria vaccine had 65 percent fewer infections, as measured by the presence of parasite in the bloodstream, over a six-month period compared with those who did not receive the vaccine.

The success of the vaccine was seen as “a hopeful beginning,” William Collins and John Barnwell, malaria experts at the US Centers for Disease Control and Prevention, wrote in a commentary accompanying the studies in The New England Journal of Medicine. However, they added that the studies were carried in countries where use of bed nets and anti-malaria drugs has dramatically reduced the number of malaria cases. The vaccine has to be tested in countries with higher rates of malaria, the scientists noted.