Researchers Used Mosquitos To Deliver Malaria Vaccines

What if mosquitoes could deliver not just the disease but the protection to an infection that kills hundreds of thousands of people annually?

"The mosquito is one of the deadliest animals on the planet," declared two South African researchers in a recent Nature article. This tiny insect is responsible for spreading malaria, a disease that infected nearly 250 million people in 2022 and killed more than 600,000 of them. Most of the victims live in sub-Saharan Africa, with children under 5 years of age accounting for nearly 80 percent of all malaria deaths.

But what if mosquitoes could deliver not just the disease but the protection? In a groundbreaking proof-of-concept clinical
trial, researchers in the Netherlands recruited mosquitoes to deliver an antimalaria vaccine with each bite. As The New England Journal of Medicine reported in November, the mosquitoes were infected with attenuated malaria parasites modified to die a week after multiplying in the livers of the trial subjects bitten by the mosquitoes. Allowing the parasites to proliferate briefly in liver cells, the researchers hoped, would induce a strong protective immune system response.

Remarkably, it worked—nearly 90 percent of the subjects later bitten by mosquitoes carrying the natural malaria parasite did not contract the disease. This initial immune response suggests that the protection offered will last longer than current vaccines.

While mosquitoes as vaccine-delivery systems might sound futuristic, the concept has opened a new frontier in malaria prevention. For practical use, the next step is to test and develop an injectable vaccine using the modified parasites. If successful,
this could revolutionize how doctors approach mass immunization efforts.

Meanwhile, progress is already being made with more conventional vaccines. After decades of effort, two safe and effective malaria vaccines for children have been approved since 2021. These vaccines reduce clinical malaria cases by more than half in the 12 months following the full administration of four doses. They are particularly effective during the high-transmission rainy season, cutting cases by three-quarters. But frequent booster shots are needed, since protection lasts only about a year.

The World Health Organization projects rapid adoption of these vaccines, with plans to administer 40 million to 60 million doses annually by 2026 and 80 million to 100 million doses annually by 2030. This represents a massive public health campaign in some of the world's poorest countries.

As the fight against malaria continues, the combination of traditional vaccines and
innovations such as mosquito-delivered immunizations brings renewed hope to combating one of humanity's oldest and deadliest foes.