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Potential Malaria Vaccine Offers Hope

This undated photo supplied by WGBH/Nova shows a mosquito at work.
A new potential malaria vaccine has been found to be safe and effective, according to the results of an early-stage clinical trial published this month in the journal Science.

The vaccine, known as PfSPZ, is composed of live but weakened elements of the most deadly of the malaria-causing parasites.

Malaria is transmitted to humans by the bite of an infected mosquito. After the bite occurs, immature malaria parasites travel to the liver, where they multiply, and then spread through the bloodstream. That is when symptoms develop.

According to the chief scientist in the study, Dr. Anthony Fauci, the PfSPZ vaccine was tested on 40 healthy adults, who showed no severe adverse effects associated with the vaccine.

Three weeks later, they were bitten by five mosquitoes carrying the malaria strain that the vaccine was based on. Only three of the 15 participants who received the higher dosages of the vaccine became infected. Among those who received the lower dosage and those who received no vaccine, virtually all participants became infected.

While Dr. Fauci said researchers were very pleased by the apparent effectiveness of the vaccine in those who received the higher dosages, more work is needed before the vaccine might be available commercially.

One major challenge is that the trial vaccine was injected directly into participants' bloodstreams, which is not practical for mass vaccination.

PfSPZ was developed by scientists at a biotech company in the US called Sanaria Inc. Researchers with the National Institute of Health, a US government agency, led the clinical study of the vaccine.