Future malaria vaccine could come from Seattle studies

The World Health Organization says a malaria vaccine should be given to children across Africa. The recommendation marks an historic first in the effort to slow the parasitic disease in the geographic region where it poses the greatest threat. Malaria is transmitted to people through certain types of mosquitoes. It is especially prevalent in Africa, but about half the world's population is at risk of the disease-causing parasite.

Rebekah Reynolds, a research scientist at the Murphy Lab, examines a mosquito specimen.
at the Murphy Lab, examines a mosquito specimen.

Work to curb malaria also has strong ties to the Pacific Northwest, with a UW School of Medicine laboratory dedicated to malaria research. Dr. Sean Murphy is celebrating this week’s WHO endorsement but says more solutions still will be needed.

“It's a big step forward. It's a great achievement, but it does not mean the fight against malaria is over," says Murphy. “It does not mean that we don't need more work on vaccines that are more effective.”

The vaccine making headlines is called RTS,S (marketed under the name Mosquirix) – which was developed more than 30 years ago. This vaccine has already been given to more than 800,000 children across Africa since 2019. The vaccine is about 30% effective and requires administering up to four doses.

Murphy’s team hopes a higher-efficacy answer could stem from a “prime-and-trap” method, which harnesses white blood cells known as T cells to attack a malaria infection in its earliest stages, before symptoms arise. The strategy focuses on directing these defender T cells to the liver, an organ which scientists understand malaria parasites to initially target as a place to replicate. With liver-specific directions, T cells are positioned to stave off parasites before they can multiply in that organ and thereby prevent them from going on to infect red blood cells. That is the stage that causes serious sickness and can threaten death.

“If you think of the liver like a cubic block, like a city street, the T cells are police,” says Murphy. “And if the parasite comes along, then [the T cells] can sound the alarm, and hopefully in the next four or five days that follow, the infected cells will be eliminated.”

The Murphy Lab has reported successful testing of this vaccine method in mice with just two doses. More testing is needed before a “prime-and-trap” vaccine could reach human trials, but that future step would also likely happen in the Seattle area.

“This is a very unique resource, and the people who really make it possible are all the volunteers, who are people in Seattle, who sign up to come in and test vaccines on behalf of people halfway around the world,” says Murphy.

Learn more about the Seattle Malaria Clinical Trials Center.

UW Medicine