Study: Experimental Vaccine Cuts Malaria Cases in Half

BY Talea Miller  October 18, 2011 at 1:51 PM EST


Child with severe malaria in Tanzania. Photo by Talea Miller/NewsHour.

For the first time, Phase III results of an experimental malaria vaccine showed significant protection against the deadly disease, raising hopes that a vaccine could be in use as early as 2015.

The vaccine, called RTS,S, reduced the risk of malaria infection in children ages 5 to 17 months by 56 percent and the risk of severe malaria by 47 percent. The analysis is based on data collected from 6,000 children in seven countries over one year.

“This is remarkable when you consider there has never been a successful vaccine against a human parasite nor obviously against malaria,” said Tsiri Agbenyega, a principal investigator of the research, which is a partnership between GlaxoSmithKline and the PATH Malaria Vaccine Initiative, with major funding from the Bill and Melinda Gates Foundation.* “This potentially translates into tens of millions of malaria cases in children being averted.”

More than half of the world’s population is at risk of malaria infection, and the parasitic disease kills nearly 800,000 people each year. Young children living in sub-Saharan Africa are the most vulnerable to the disease.

While the efficacy of the vaccine in these preliminary results was in line with Phase II outcomes, it does raise questions about how the vaccine could be used. Without complete protection, health agencies would have to balance the benefits and risks of the vaccine, Agbenyega said, and the vaccine would have to be used in coordination with other malaria prevention methods like insecticide-treated bednets.

“Obviously one would want to have a higher efficacy for severe disease,” said Agbenyega, “but we are still hoping to improve the vaccine as we go along.”

A smaller-scale analysis released with the results showed that protection against severe malaria dropped to 35 percent when younger infants were factored in, but David Poland, a spokesperson from the PATH Malaria Vaccine Initiative, said the 35 percent figure was derived from incomplete data — from just a few hundred cases — and has limited implications. Final results from the younger infant trial group will not be available until 2012 and will be key to establishing a more accurate picture, he said.

“We are looking into that, there are several hypotheses about why that number came out where it did,” Poland said. “But we really need to get the results in 2012 to peg down what is happening.”

Andrew Witty, CEO of GSK, called the protection provided in the trial a milestone in the decades of attempts at a malaria vaccine and said the drug manufacturer is hopeful a vaccine could be delivered as early as 2015.

“Our intention is to supply this vaccine at the lowest price possible. We are committed to providing this vaccine at the cost of goods plus a 5 percent markup,” he said. It is too early in the process to determine what that cost could be, he added.

The 5 percent gain would be reinvested in GSK research for neglected diseases for the developing world. The vaccine is being produced in Europe and should it be approved, Witty said, about 30 million doses — covering 10 million children — would be available in the first year. The company would look into cost-saving measures like producing the vaccine in Africa or India.

“I’ve got every confidence we can get this price to a level that makes it very viable for donors to consider should they decide to prioritize malaria,” Witty said.

The vaccine works by triggering the immune system against the malaria parasite, which is introduced into the body by mosquitoes. RTS,S targets the parasite as it enters the bloodstream and liver, preventing the parasite from multiplying in the liver and going on to infect red blood cells.

For the record, the NewsHour’s global health coverage is funded by a grant from the Bill and Melinda Gates Foundation.