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19 October 2011

Vaccine reduces malaria risk by half

A vaccine against malaria has been shown to reduce African children's risk of acquiring the disease by about half, according to the results of an ongoing phase III trial released.

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A vaccine against malaria has been shown to reduce African children's risk of acquiring the disease by about half, according to the first results of an ongoing phase III trial released.

The vaccine – known as RTS,S – is made by the British pharmaceutical giant GlaxoSmithKline's lab in Belgium, and is the first of its kind to attempt to block a parasite, rather than bacteria or viruses.

The trial, under way at 11 sites in sub-Saharan Africa, showed that children aged five to 17 months who received three doses of the vaccine saw a 56% lower risk of developing clinical malaria, which causes high fever and chills.

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% lower risk.

Fight not over yet

"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 Hospital in Kumasi, Ghana.

"While these results are encouraging, we still have a way to go," he told reporters.

The analysis was done with data from 6,000 children in the trial over a 12-month follow up after vaccination.

More data is needed from the younger age group – infants from six to 12 weeks – to better assess how well it works, experts said. Additional results from the younger set are due next year.

Gates foundation enthusiastic

The results are published online in the New England Journal of Medicine, and were simultaneously announced at the Malaria Forum hosted by the Bill & Melinda Gates Foundation in Seattle, Washington.

Asked by a reporter whether the Gates Foundation would get behind a vaccine with a success rate of only about half, Regina Rabinovich, director for infectious diseases at the foundation's global health programme, was circumspect.

"This is a key question. The group will ultimately want to understand efficacy, duration and safety," she said, adding she was enthusiastic about the results so far and was awaiting further data.

"Would I prefer to see a 100% effective vaccine? Absolutely."

Largest trial to date

More than 15,000 children in seven African countries are enrolled in the trial, which is set to continue for two more years.

The vaccine was administered to children who are in areas with other interventions against malaria, such as bed nets and spraying.

The vaccine was created in 1987 in GlaxoSmithKline Bio's lab in Belgium. Testing began on healthy adults in Belgium and the United States in 1992, before the first Africa study started in Gambia in 1998.

Trial sites are now located in Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania, including 15,460 infants and young children in what GSK described as the largest malaria vaccine trial to date.

A problem for the poor

The vaccine works by triggering the immune system to defend itself against Plasmodium falciparum, the deadliest type of malaria parasite which is transmitted by mosquitoes.

Several questions remain, including how the long the vaccine may last, how well it works in small babies, and how much it will cost, said Seth Berkley, CEO of the Global Alliance for Vaccines and Immunization (GAVI Alliance).

"From a public health point of view, this is a disease that has been around since ancient times. It is a huge problem for the poorest of the poor, and there has been a search for vaccines for as long as I can remember," he told AFP.

"So to have success, even if not perfect, is a really big deal."

Vaccine available by 2015

GlaxoSmithKline CEO Andrew Witty said the company had already invested R2.401 billion in the development of the vaccine and aims to produce it at a low cost with no profit for the manufacturer.

"It is humbling to think that half of the world population is exposed to some form of malaria," Witty said, referring to statistics from the World Health Organization that show malaria claimed 781,000 lives in 2009.

About 90% of malaria deaths each year occur in Africa and 92% of those are in children under five.

"We are hopeful that we will be able to bring this vaccine to children in Africa by 2015," Witty said.

Side effects included fever and swelling at injection site, "what you would typically see in other childhood vaccinations," said Agbenyega.

(Sapa, October 2011) 

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Malaria

Malaria vaccine

 

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