An experimental malaria vaccine was able to reduce the rate of infection and disease in children by 53 to 65 percent in two clinical trials conducted in Africa, according to studies released Monday.
Researchers have been trying to develop a vaccine for the deadly, mosquito-borne illness which kills nearly a million people a year and sickens 250 million others for more than 70 years.
"This is the first candidate malaria vaccine to show significant protect in laboratory and field-based clinical studies," William Collins and John Barnwell of the Centers for Disease and Prevention wrote in an editorial accompanying the studies published in the New England Journal of Medicine.
"It is, indeed, a hopeful beginning."
The vaccine was first developed by GlaxoSmithKline in the late 1980's and initially tested in US volunteers. The drug company entered a partnership with the nonprofit group PATH Malaria Vaccine Initiative in 2001 to test the vaccine in African children.
They are on track to start the final phase of clinical trials at sites across Africa early next year to confirm and evaluate the vaccine's efficacy, better determine its duration and closely monitor its safety.
In the trials published Monday, researchers separately studied two groups of children in Kenya and Tanzania.
In the first study, researched enrolled 340 infants under 12 months of age in Tanzania to determine whether the malaria vaccine - RTS,S/AS02 - interfered with the immune response to a common set of childhood vaccines which are administered at eight, 12 and 16 weeks of age.
Half the infants were given the malaria vaccine along with their regular shots while the others were immunized against hepatitis B along with their regular shots.
The researchers found it was safe to administer the vaccine in tandem with the other vaccines administered with the World Health Organization's immunization program.
They also showed a 65 percent drop in the number of malaria infections and a 59 percent drop in incidents of the infection developing into clinical disease over a six month period.
"This result suggests that it will be feasible to provide RTS,S together with other routine children's vaccines, making its deliver in endemic areas much easier and less costly," Collins and Barnwell wrote in the editorial.
In the second trial, 894 children aged five to 17 months were enrolled to test the safety and effectiveness of the vaccine using a different adjuvant, which is meant to enhance the immune response to the vaccine.
Half the children received the malaria vaccine and the other half received a rabies vaccine.
The researchers found this variant of the vaccine reduced clinical malaria episodes by 53 percent for up to an average of eight months.
Earlier studies in Mozambique using a different adjuvant showed a 35 percent reductions in clinical cases for 18 months.
"We are closer than ever before to developing a malaria vaccine for children in Africa," said Christian Loucq, director of the PATH Malaria Vaccine Initiative.
"History has shown that vaccines are the most powerful tool to control and eliminate infectious diseases. Clearly, the world urgently needs a safe and effective vaccine to win the war against this terrible disease."