Two vaccine candidates have been shown to be effective — in one case, 100 percent effective — in preventing malaria.
The biotech firm Sanaria Inc. of Rockville, Maryland, developed the vaccines. They prime the immune system against the malaria parasite by introducing live but weakened sporozoites — the earliest spore stage of the parasite — which infected mosquitoes inject into the body, beginning the cycle of disease.
Both vaccines target Plasmodium falciparum, the most common and deadly form of the disease.
In the more successful of the two trials, carried out in Germany, varying doses of the live-attenuated vaccine, weakened by a chemotherapy agent, were injected into 27 healthy volunteers, while another group of 15 was given a placebo.
The participants were then exposed to P. falciparum parasites between eight and 10 weeks after the last vaccine dose.
Stephen Hoffman, Sanaria’s chief executive and scientific officer, said results from nine of the participants who received the highest vaccine dose surprised the researchers.
“We got 100 percent protection against malaria at 10 weeks, 2½ weeks after the last dose of the vaccine,” he said. “That is really beginning to look like something quite extraordinary and that’s never been done before.”
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