Malaria vaccine trial hope9th December 2008
Two trials of a malaria vaccine in Africa are showing promising results.
Children receiving the RTS,S vaccine in both trials more than halved their chances of contracting malaria, compared with children who did not get the jab.
Led by Philip Bejon of the University of Oxford, the trials built on earlier and smaller trials of the vaccine, and a larger, definitive trial looks set to follow.
Published in the New England Journal of Medicine, Bejon's team trialled the vaccine, which was developed by GlaxoSmithKline with support from the Malaria Vaccine Initiative.
It works by priming the immune system to combat the Plasmodium falciparum parasite when it is injected into the bloodstream of humans by feeding mosquitoes. It breaks the life cycle between initial infection and the liver, which is where severe disease can occur.
Researchers gave either the new vaccine or a control vaccine to 809 children aged five to 17 months at centres in Kenya and Tanzania.
Only 32 of the 402 who received the malaria jab developed the disease over the eight-month period of the trial. More than twice as many - 66 out of 407 - contracted malaria in the control group.
The disease also took longer to develop in those who received the vaccine, researchers noted, concluding that the vaccine had an overall efficiency of 53% if both effects were taken into account. The risk of malaria was roughly halved by the vaccine, Bejon said.
Another trial led by Salim Abdulla of the Ifakara Health Institute in Bagamoyo, Tanzania, the vaccine performed even better in a trial involving 340 infants in the country.
Abdulla said the efficiency was 65% in this case. Given that an estimated 18 million cases occurred in Tanzania alone every year, such a vaccine could greatly reduce deaths and other consequences from malaria.
Researchers say the vaccine is compatible with all current immunisation programmes offered to children, including tetanus, diphtheria and whooping cough.
William Collins of the malaria branch of the US Centers for Disease Control in Atlanta, Georgia called the results promising, saying he hoped the vaccine would now progress swiftly to a larger trial.
He called for trials in areas of Africa where malaria is much more rampant than in the regions in which these trials took place, pointing out that intensive programmes to combat malaria in Tanzania and Kenya by giving people pesticide-coated bed nets have already reduced rates of malaria by 50%.
He noted that the vaccine was still efficacious despite the fact that it only mimicked one aspect of the plasmodium parasite's life cycle, suggesting that future vaccines might target multiple stages, giving even greater protection.
Bejon said further data was also needed on how long the vaccine lasted, once injected.
Joe Cohen of GlaxoSmithKline Biologicals said that a much larger study of RTS,S is now almost certain to go ahead in early 2009 at 11 different sites in Africa involving 16,000 infants and babies.
Cohen said the sites had been chosen for their different levels of malaria, so the vaccine would get a full workout in many environments. He said he was confident its effects will last for several years.
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Title: Malaria vaccine trial hope
Author: Luisetta Mudie
Article Id: 9506
Date Added: 9th Dec 2008