Malaria Vaccine Shows Signs of Promise, US Health Officials Report

US health officials announced Thursday that an investigational malaria vaccine has shown to be both safe and effective.

Known as PfSPZ Vaccine, the drug includes live though weakened sporozites of the species Plasmodium falciparum, the most deadly of the malaria-causing parasites.

The Phase I trial included 57 adults between 18 and 45 years old, 40 of which received the vaccine which was delivered intravenously in varying doses.

Later blood measurements showed that the participants who received a higher total dosage of the vaccine generated more antibodies against malaria and more T cells, a type of immune system cell, specific to the vaccine.

In order to test whether or not the vaccine was capable of preventing malaria infection, participants -- including those who were not vaccinated -- were exposed to bites by five mosquitoes carrying the P. falciparum strain. All were then monitored as outpatients for seven days and admitted to the National Institute of Health Clinical Center until they were officially diagnosed with malaria, treated and cured.

As a result, the researchers found that the higher doses of PfSPZ Vaccine showed evidence of protection against malaria infection: only three of the 15 participants who received higher doses became infected, versus 16 of the 17 who received lower amounts of the vaccine. Of the 12 who received no vaccine, 11 became infected.

The fact that the vaccine has to be injected intravenously is a rare measure but, as Dr. William Schaffner, head of the preventive medicine department at Vanderbilt University's medical school, told CNN, "desperate times call for desperate measures."

Going forward, research to evaluate the vaccine's different dose schedules as well as possible protection against other Plasmodium strains and the durability of protection are all needed.

"This is not a vaccine that's ready for travelers to the developing world anytime soon," Schaffner explained. "However, from the point of view of science dealing with one of the big three infectious causes of death around the world, it's a notable advance. And everybody will be holding their breath, watching to see whether this next trial works and how well it works."