Malaria vaccine protects for up to a year

According to the latest WHO estimates, released in December 2015, there were 214 million cases of malaria in 2015 and 438 000 deaths. At the moment there is no vaccine.

But now, a new study – a Phase 1 trial – by researchers at the University of Maryland School of Medicine (USA) has found that an experimental malaria vaccine protected adults from infection for more than a year[1]. The vaccine was an attenuated Plasmodium falciparum (Pf) sporozoite (SPZ) vaccine (shortened to PfSPZ Vaccine).

"These results are really important," said Kirsten E. Lyke, a researcher at the University of Maryland School of Medicine. "Malaria has such a devastating effect on children, especially in Africa. This vaccine has the potential to help travelers, military personnel and children in malaria-endemic areas."

Lyke and her colleagues, conducted a clinical evaluation of the vaccine, which involved exposing a small number of willing healthy adults to the malaria-causing parasite Plasmodium falciparum in a controlled setting. The parasite is transmitted to humans via the bite of infected mosquitos. The PfSPZ Vaccine consists of live, but weakened (attenuated), Plasmodium falciparum, specifically, the early developmental form of the parasite.

Previous research had shown that the vaccine worked for three weeks after immunization[2]. This study analyzed its longer term effects. The trial enrolled 101 healthy adults aged 18 to 45 years, who had never had malaria. Of these, 59 participants received the vaccine, while 32 participants were not vaccinated.
Participants were exposed to the bites of mosquitoes carrying the same Plasmodium falciparum strain from which the vaccine was derived. IV administration appears to provide better protection than intramuscular injection, both in the short and long term. Overall, the study found that the vaccine provided protection for up to a year in more than half (55 percent) of subjects. In those people, it appeared to provide sterile protection, meaning the subjects not only didn't get malaria, but also could not further transmit malaria.

[1] Ishizuka et al: Protection against malaria at 1 year and immune correlates following PfSPZ vaccination in Nature Medicine – 2016
[2] Seder et al: Protection Against Malaria by Intravenous Immunization with a Nonreplicating Sporozoite Vaccine in Science – 2013

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