This idea has been known since the nineteen sixties. But Mr. Seder says a discovery by a researcher at a vaccine company cleared the way for progress.
ROBERT SEDER: "The major breakthrough here was that my collaborator, Stephen Hoffman at Sanaria, developed a method where he could isolate the sporozoites and purify them so that they could administer it as a vaccine to humans. And no one thought that that was possible."
But no one knew either if the weakened sporozoites would activate the immune system to protect against malaria. So researchers tested it on volunteers and found that it was safe -- there were only minor side effects. But it was not very effective. Only two out of forty-four volunteers were protected when bitten by malaria-infected mosquitoes.
To find out why, the researchers tested the vaccine on laboratory animals. They decided that the problem was the way the vaccine had been given to the volunteers. It was injected into the skin, to simulate the bite of a mosquito. Mr. Seder says it would have been more effective if it had been given directly into the blood.
However, vaccines are generally given by mouth or injected into the skin or muscle. Having to inject it into the blood could make vaccination programs more difficult if the vaccine is approved for general use. Mr. Seder says it is also too soon to know how much the vaccine would cost.
For now, more testing is needed. A report on the study appeared in the journal Science.
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2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25