Scientists at the Kenya Medical Research Institute in Kisumu are taking part in clinical trials of RTS,S—the most clinically advanced malaria vaccine candidate. Photo: PATH/Eric Becker.
With one promising vaccine in the works, PATH is building tools to develop more candidates more quickly
Inside a Seattle laboratory, courageous volunteers face off with a prolific killer: the female Anopheles mosquito. As the carrier of the malaria parasite, this tiny insect holds immense power in the search for a vaccine that can protect people from malaria infection.
To help scientists assess vaccine approaches, healthy men and women who have received a candidate malaria vaccine proffer their arms to the mosquitoes for a blood meal. Plasmodium falciparum, the most deadly type of human malaria parasite, kills hundreds of thousands of people every year, most of them children in sub-Saharan Africa. By watching volunteers become infected in a controlled environment, scientists can assess potential vaccines and garner crucial information that will help them refine vaccine approaches and ensure that the most promising move forward.
Finding potent protection
Today, there are some four dozen malaria vaccine projects at various stages of development around the world. The PATH Malaria Vaccine Initiative supports several, including RTS,S, the world’s most clinically advanced malaria vaccine candidate. Scientists are testing RTS,S among children in seven African countries in a pivotal phase 3 efficacy trial, typically one of the last steps before regulatory approval. Final results of the trial are expected in late 2014.
If you think you’re too small to make a difference, you haven’t spent a night with a mosquito.
At the same time, the PATH Malaria Vaccine Initiative is both building on progress made with RTS,S and evaluating different paths toward immunization. We’re pursuing this multipronged approach because developing a malaria vaccine poses unusual challenges. For one thing, a successful vaccine candidate must protect people against a parasite—something that’s never been done before.
As the number of potential malaria vaccine candidates has increased, scientists need new and better technologies to assess potential efficacy. One way we’re contributing to technology development is through support of the Malaria Clinical Trials Center at the Seattle Biomedical Research Institute, which offers early-stage testing in humans that allows scientists to observe whether a candidate vaccine can prevent or delay infection.
Unlocking the secrets of immunity
Developing effective malaria vaccines is a priority of the global health community, and refinement and development of methods for consistently evaluating vaccine candidates is crucial to success. PATH supports development of evaluation technologies, including laboratory tools that can yield consistent results, so that early in the testing of a vaccine approach, scientists can obtain preliminary evidence of how different formulations prompt the human immune system to resist a parasite invasion.
Evaluation technologies, including challenge models like the one being used in Seattle, can provide researchers with the information they need to decide whether to move a particular vaccine project into the next stage of testing, including testing in regions that continue to suffer from malaria.