Malaria Vaccine Offers Hope in Clinical Trials

According to the U.S. researchers, an experimental malaria vaccine appears to offer protection against infection in healthy adults.

Researchers make the vaccine, called PfSPZ, by using samples of Plasmodium falciparum, the parasite that causes the malaria infection. These samples, although still live, were weakened by using radiation and then they were frozen. Photo: Caritas Europa/Flickr

The World Health Organization says that mosquitoes, known for biting and then spreading malaria, which is a potentially-fatal disease that affected 26 million people worldwide in 2011.

According to the Centers for Disease Control and Prevention there are about 1,500 cases of malaria in the United States every year; however, this is mainly due to travelers who are returning from countries where malaria transmissions occur – most malaria transmissions occur in the sub-Saharan Africa and South Asia, reports Decoded Science.

About 3.3 billion people worldwide are at risk for the disease with people living in the poorest countries the most vulnerable. Only about 1,500 cases of malaria are reported in the U.S. each year despite the virus being eliminated from the country in the early 1950’s, the Centers for Disease Control and Prevention adds.

There is currently no vaccine for malaria, which is caused by five different strains of Plasmodium, a parasite that lives in the gut of the female Anopheles mosquito and passes to humans through her bite.

Scientists are hopeful they’re getting closer to a malaria vaccine following a new study in which an experimental shot called the “PfSPZ Vaccine” was found to be safe and effective against the mosquito-borne disease.

The vaccine, known as PfSPZ Vaccine, was developed by scientists at Sanaria Inc., of Rockville, Md. The clinical evaluation was conducted by researchers at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and their collaborators at the Walter Reed Army Institute of Research, Silver Spring, Md., and the Naval Medical Research Center, Bethesda, Md.

The vaccine is composed of live but weakened sporozoites of the species Plasmodium falciparum, the most deadly of the malaria-causing parasites.

The researchers also say early results indicate the vaccine is safe and “generated an immune response” in the group of volunteers tested. Researchers found the vaccine, which protected 12 out of 15 patients from the disease, when given in high doses.

The method is unusual because it involves injecting live but weakened malaria-causing parasites directly into patients to trigger immunity. The researchers gave the vaccine intravenously in either four or five doses. Three weeks after getting the vaccine, volunteers were bitten by mosquitoes that were infected with malaria.

Fifty-seven adults between 18 and 45 years old took part in Phase One of the trial. Forty received the vaccine and 17 did not. Some of those who received the vaccine were given increasing doses. After seven days of monitoring, “no severe adverse effects associated with the vaccine occurred, and no malaria infections related to vaccination were observed.”

The researchers found that the higher dosages of PfSPZ Vaccine were associated with protection against malaria infection. Only three of the 15 participants who received higher dosages of the vaccine became infected, compared to 16 of 17 participants in the lower dosage group who became infected. Among the 12 participants who received no vaccine, 11 participants became infected after mosquito challenge.

Furthermore, those who received the most vaccine generated more antibodies against malaria, researchers said.

“These trial results are a promising first step in generating high-level protection against malaria, and they allow for future studies to optimize the dose, schedule and delivery route of the candidate vaccine,” said lead trial investigator Dr. Robert Seder, chief of cellular immunology at the NIAID Vaccine Research Center in Bethesda, Md.

He added: “We were excited and thrilled by the result, but it is important that we repeat it, extend it and do it in larger numbers.”

Stephen Hoffman, CEO of Sanaria, has been on a quest to find a malaria vaccine for decades. His unusual approach of using the whole weakened form of the parasite dates back to experiments he carried out in the 1970s. Now many experiments later, the same idea is behind the PfSPZ vaccine tested in this latest trial.

Share this article

We welcome comments that advance the story directly or with relevant tangential information. We try to block comments that use offensive language, all capital letters or appear to be spam, and we review comments frequently to ensure they meet our standards. If you see a comment that you believe is irrelevant or inappropriate, you can flag it to our editors by using the report abuse links. Views expressed in the comments do not represent those of Coinspeaker Ltd.