Malaria vaccine shows promise in two trials, but has a way to go

Health worker prepares anti-malaria medications.

A new vaccine may help protect people against malaria. Two studies on variants of the same vaccine released today found that it is effective at preventing malaria. The promising results are tempered by the fact that roughly 100 people participated in the two studies and they provided protection well below the 75 percent threshold set by the World Health Organization.

“We got the highest level of protection ever seen in a malaria vaccine,” Sanaria founder Stephen Hoffman told Humanosphere. “It is better than ever reported, but it is not good enough.”

Sanaria is the U.S.-based pharmaceutical company that developed the PfSPZ vaccine against malaria. It is a novel solution because it uses the parasite that causes malaria to provide protection. The formulation is similar to the use of multiple virus strains found in polio and pneumococcal vaccines, Hoffman said.

In Germany, nine people were given the chemoattenuated PfSPZ vaccine and 13 were not. The vaccine group also received the antimalarial drug chloroquine to prevent the intentionally injected parasites from forming in their blood.  All nine people given the vaccine did not get malaria after being exposed to it 10 weeks after treatment. The 13 not vaccinated all had malaria in their bloodstream.

A separate study in Mali treated 44 people with a non-chemoattenuated form of the vaccine and compared malaria infection against 44 people who received a saline placebo. Researchers followed up 24 weeks later and found that 93 percent of the placebo group and 66 percent of the vaccine group had one or more infections. That means the vaccine was 29 percent effective at preventing malaria – a long way from Hoffman’s goal of developing a vaccine that is 80 percent effective.

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“Our goal is to have a vaccine we can use to treat the whole population that can stop transmission and eliminate of malaria,” he said. “We are on a quest to give a vaccine that does three things: safe, well tolerated and has a high level of efficacy.”

None of the participants in either study experienced side effects. Hoffman saw that as the most promising news out of the findings. The focus now is to hone the vaccine regimen and improve efficacy. Trials in Kenya, Tanzania, Equatorial Guinea, Burkina Faso, Germany, the U.S. and Mali are under way to find what works best. The Kenya trial, for example, features three different treatment groups.

Companies and organizations attempting to develop a malaria vaccine have experienced setbacks and underwhelming results in recent years. The phase-two clinical trial in Kenya for GlaxoSmithKline’s (GSK) Mosquirix (RTS,S) vaccine showed just a 4 percent effectiveness 7 years after infants were given the vaccine. It was bad news a year after a study on the vaccine found it was effective 28 percent in children and 18 percent in infants.

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The good news is that scientists are finding ways to prevent malaria at least some of the time. But achieving the goal of elimination requires a highly effective vaccine, said Hoffman. He admitted that vaccines are not a silver bullet solution, but said that the eradication of small pox and gains against polio are driven by effective vaccines.

“We are under no illusions how hard it is to do this. But we are encouraged by the results we have seen,” said Hoffman.

If health workers could come into an area and fully immunize the population with a highly effective vaccine, it would be possible to wipe out the parasites with the drug. After six months there would be no parasites in the area, he said. That effectively ends transmission, saving lives and preventing people from getting sick.

“Malaria is the mother and daddy of all tropical infectious diseases,” he said. “I have worked on all parts of treating and preventing tropical infectious diseases. As a physician what could be more aspirational than trying to prevent a vaccine that kills up to 1 million people a year and impacts hundreds of millions.”

“What could be a more wonderful objective?”

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Tom Murphy

Tom Murphy is a New Hampshire-based reporter for Humanosphere. Before joining Humanosphere, Tom founded and edited the aid blog A View From the Cave. His work has appeared in Foreign Policy, the Huffington Post, the Guardian, GlobalPost and Christian Science Monitor. He tweets at @viewfromthecave. Contact him at tmurphy[at]humanosphere.org.