Hope rises for effective malaria vaccine
Trial drug plasmodium vivax shows promise in human trials
THERE is renewed hope for an effective malaria vaccine as the first candidate against plasmodium vivax was well tolerated in all volunteers and generated robust immune responses.
The study published Monday in the journal PLOS Neglected Tropical Diseases, however, noted that while the vaccine candidate did not prevent malaria infection, it did significantly delayed parasitemia in 59 per cent of vaccinated subjects.
The vaccine candidate developed by Walter Reed Army Institute of Research (WRAIR) United States and tested jointly with GlaxoSmithKline (GSK) to prevent vivax malaria infection is the first-in-human study of its kind under an investigational new drug application with the US Food and Drug Administration (FDA).
The results of testing a Plasmodium vivax malaria vaccine candidate in a human challenge model published recently by WRAIR United States researchers showed that the investigators immunized 30 volunteers with three doses of the vaccine candidate.
According to the study, a vaccine to prevent infection and disease caused by P. vivax is critical to reduce sickness and mortality from vivax malaria, a common cause of malaria among deployed service members. While malaria no longer poses a significant threat in developed countries, it affects millions of people every year around the world.
P. vivax malaria is challenging to control because it can be dormant, causing no symptoms, and then become active causing symptomatic malaria weeks to months after initial infection.
Malaria is only transmitted through the bite of a female mosquito. Immunized volunteers took part in WRAIR’s well-established controlled human malaria infection (CHMI) model where they were bitten by malaria-infected mosquitoes. The efficacy of the vaccine candidate was then determined based on whether or not volunteers developed malaria by looking at blood smears or if it took longer for malaria parasites to appear in the blood.
The study’s lead investigator, Lt. Col. Jason W. Bennett, said: “This study represents the first vaccine study to test the effectiveness of a P. vivax vaccine candidate in humans using controlled human malaria infection.”
The study’s results were published Monday in the journal PLOS Neglected Tropical Diseases. Unlike P. falciparum where a CHMI model is well established, the P. vivax CHMI model must rely on blood donations from infected humans to initiate infections in mosquitoes.
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