The search for the world's first malaria vaccine is inching closer with early results released from the clinical trial showing it cut risk by about half in African children.
The vaccine known as RTS,S has been developed by pharmaceutical giant GlaxoSmithKline and is the first of its kind to block parasites rather than bacteria or viruses.
Experts have hailed the phase three trial, under way at 11 sites in sub-Saharan Africa, as a promising step toward eradicating the mosquito-borne disease that kills almost 800,000 people year, most of which are children.
"This is remarkable when you consider that there has never been a successful vaccine against a human parasite," said Tsiri Agbenyega, who chairs the RTS,S Clinical Trials Partnership and heads malaria research at Komfo-Anokye Teaching Hospital in Kumasi, Ghana.
The analysis was done with data from 6,000 children in the trial over a 12-month follow up after vaccination.
Children aged five to 17 months who received three doses of the vaccine saw a 56 percent lower risk of developing clinical malaria, which causes high fever and chills, according to the study.
When it came to severe malaria -- the stage of the illness that can be fatal and reaches the blood, brain or kidneys -- those who received the vaccine showed a 47 percent lower risk.
"While these results are encouraging, we still have a ways to go," Agbenyega told reporters.
More data is needed from the younger age group -- infants aged six to 12 weeks -- to better assess how well it works in this particularly vulnerable group, experts said. Additional results from the younger set are due next year.
The vaccine works by triggering the immune system to defend the body against Plasmodium falciparum, the deadliest type of malaria parasite.
Side effects included fever and swelling at injection site, "what you would typically see in other childhood vaccinations," Agbenyega said.
In a statement, Microsoft tycoon Bill Gates said the findings were a "huge milestone".
The philanthropist, who has donated billions of dollars towards vaccines in the developing world, believes the vaccine "has the potential to protect millions of children and save thousands of lives."
According to the World Health Organization, malaria claimed 781,000 lives in 2009. About 90 per cent of malaria deaths each year occur in Africa and 92 per cent of those are children less than five years old.
