Sanaria's experimental malaria vaccine displays effectiveness in early-stage study

Study data published Thursday in the journal Science showed that Sanaria's PfSPZ experimental malaria vaccine was protective against the disease in 12 of 15 patients who received high doses in a Phase I trial. "We were excited and thrilled by the result, but it is important that we repeat it, extend it and do it in larger numbers," cautioned study author Robert Seder.

The study enrolled 57 volunteers with no previous history of malaria, aged between 18 and 45 years. The researchers intravenously administered differing doses of the vaccine, which consists of live, weakened, purified sporozoites of Plasmodium falciparum, to 40 of the volunteers, after which some of the volunteers were exposed to malaria-carrying mosquitoes. Among the six volunteers who received the full five-shot regimen, none developed malaria after exposure to malaria-carrying mosquitoes, and only three of nine patients who received a four-shot regimen developed malaria after exposure to the mosquitos. Conversely, 16 of 17 people in the lower dosage group and five of six unvaccinated controls developed malaria after exposure to infected mosquitoes.

"In this trial, we showed in principle that sporozoites can be developed into a malaria vaccine that confers high levels of protection and is made using the good manufacturing practices that are required for vaccine licensure," remarked Seder. However, the vaccine only displayed effectiveness when administered intravenously, as prior tests of vaccination via standard routes of administration failed to reveal as high levels of protection. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, noted that intravenous vaccination is plausible in certain special populations but that the logistics of a mass intravenous vaccination programme would be "somewhat complicated."

A number of follow-up studies have been planned, including assessments of the duration of immunity and of different dose schedules. Researchers also plan to investigate whether the subcutaneous or intradermal administration of high doses of the vaccine can confer similar protection as observed in the current study.

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