A new malaria vaccine has shown 100 percent effectiveness at preventing the infection in a small trial, The New York Times reports. This encouraging milestone in the fight against a disease that can worsen the course of HIV, and vice versa, is tempered by the fact that the vaccine's delivery methods are highly impractical for parts of the world where a vaccine is needed most. The vaccine also comes with a high price tag, and there is no data yet on how long it offers protection.

More than 200 million people in poor countries are infected with malaria annually, about 660,000 of whom die of the disease.

Publishing their results in the journal Science, researchers gave five intravenous doses of the vaccine during a 20-week period to six study participants, and four doses to nine participants during the same timeframe. There was also a control group of six participants who received no vaccine.

None of the six participants receiving five doses got malaria when bitten by infected mosquitos. Three out of the nine participants who received four doses were protected. Five out of the six members of the control group were infected.

The vaccine was constructed by administering radiation to malaria-infected mosquitos, removing their salivary glands and then purifying the parasites in the salvia, which had been weakened by the radiation.

To read the New York Times story, click here.

To read the Science abstract, click here.