View Full Version : Malaria Vaccine for Kids shows some promise

11-15-2005, 17:12
Hopeful news regarding Malaria Vaccine for children. Something they literally pulled off the back of the dusty shelf shelf and didn't think would work.

Tuesday, November 15, 2005

Old malaria vaccine shows new promise for children
Gates-financed study finds medicine that failed to help adults works for kids


Scientists may have finally found the first effective malaria vaccine for children.

Further positive results from an ongoing malaria vaccine trial in Africa, funded by the Bill & Melinda Gates Foundation and administered by Seattle-based PATH, are expected to be greeted with surprise -- if not cautious skepticism -- by many malaria scientists who learn of these developments today at an international research conference in Cameroon.

At stake are the lives of nearly 1 million young children, at least 2,000 per day, who now die from malaria. The Gates-funded study raises the possibility that most of these deaths could be prevented using an old vaccine the experts had once chucked as largely useless.

"Nobody expected this," said Dr. Melinda Moree, director of the Malaria Vaccine Initiative at the Program for Appropriate Technology in Health. Moree was reached yesterday by telephone at the Fourth Multilateral Initiative on Malaria meeting in Yaounde, Cameroon, where she will be among those presenting the new findings.

"Four years ago when we started this project, very few people would have predicted that this vaccine would work at all," she said.

This first candidate vaccine for the Gates-funded Malaria Vaccine Initiative was literally pulled off the back shelf as a failed experimental vaccine that had been developed 20 years ago by GlaxoSmithKline. Known as the "RTS/S" vaccine, it had already been tested in adults in Gambia and failed to show any lasting immunity against malaria.

"In adults, it was totally gone after two months," said Moree. But she and her colleagues decided it was worth funding a study in children, she said, expecting it would do little more than provide a scientific baseline for more promising experimental vaccines.

A year ago, Moree and a team of vaccine scientists led by a world-renowned malaria expert, Dr. Pedro Alonso of the University of Barcelona in Spain, reported that about 2,000 children in Mozambique who got the Glaxo vaccine showed significant immunity against malaria. After six months, the vaccinated children had 58 percent fewer cases of severe malaria and 30 percent less disease overall.

"Few expected this would last," Moree said. With most experimental vaccines, she said, the malaria parasite soon figures out a way around it and immunity wanes.

But in today's edition of the British medical journal The Lancet and at the Cameroon meeting, Alonso and his team report the startling discovery that children who received this vaccine have maintained similar levels of immunity for the last 18 months.

"It's quite surprising, really," Moree said. She said this kind of lasting immunity is long enough to justify considering moving this from the scientific realm to wider public health use.

"The first 18 months of life are when kids are most vulnerable to this infection," she said. The vaccine may show even longer persistent immunity, she said, but even if it only lasts this long it could be long enough to protect those youngest children during their riskiest period.

So why does this vaccine work for children and not adults?

"We don't know," Moree said.

It's not clear how the vaccine works at all, she said, noting that the children's antibodies to the malaria parasite decline over time -- which should be accompanied by a decline in immunity. But the immunity doesn't decline, she said, indicating another arm of the children's immune system known as the "cellular response" may be kicking in.

As the researchers continue to follow the children in Mozambique, Moree said, they will be adding new angles on the study to try to figure out what precisely is going on.

The Malaria Vaccine Initiative at PATH, which has received more than $250 million from the Gates Foundation over the past five years, is supporting a number of projects searching for an effective vaccine against malaria. PATH is a non-profit organization that specializes in international public health projects.

The Gates Foundation recently gave PATH a $107 million grant to expand testing of the Glaxo RTS/S vaccine to 10,000 children in six African countries.