Malaria kills around 400,000 people each year, and the majority are children younger than 5. The number of deaths has dropped by more than half since the beginning of the millennium, as countries have ramped up the use of mosquito nets treated with insecticide and other controls for mosquitoes, which spread the parasite that causes the disease. But in Africa, it’s likely that around four times as many people died from malaria as from COVID-19 in 2020.
A new malaria vaccine may drastically reduce the risk. In an early trial, the vaccine was 77% effective in preventing the disease, far more than any other attempted malaria vaccine in the past.
Scientists have been trying to create a vaccine for malaria for decades. The first COVID-19 vaccines, by contrast, were developed within days. “It’s been far more difficult to make a malaria vaccine,” says Adrian Hill, director of the Jenner Institute at the University of Oxford. Hill is among a group of researchers working on the new vaccine. (The Jenner Institute also developed the COVID-19 vaccine produced by AstraZeneca, using a vaccine technology that had previously also been tested for malaria.)
The virus that causes COVID-19 has 12 genes, and an obvious target is the virus’s spike protein; the malaria parasite has more than 5,000, with no clear indication of what would be best to target. The parasite has also been evolving for millions of years, creating many different strains. In areas where malaria is widespread and many people have been exposed to the parasite, creating chronic infections, it’s harder to get a strong immune response through vaccination. “In the places where you want the vaccine to work best, it works less well,” Hill says.
The new vaccine reengineers a previous malaria vaccine to “put more malaria in and less of the carrier protein,” he says. “That gave us stronger immune responses and better efficacy.” In an early small trial in Burkina Faso with 450 children, the new vaccine worked incredibly well. Of the 147 children in the trial who got a placebo, 105 contracted malaria. Of the 292 who received the vaccine, just 81 got sick. The efficacy—preventing disease 77% of the time—surpasses the World Health Organization’s goal to have a vaccine with 75% efficacy by the end of the decade.
Much larger trials are beginning now in four additional African countries, but Hill expects that the efficacy will remain similar. The larger Phase 3 trial will test safety in larger numbers. While it’s possible that the trial will discover an issue, “we’re confident that it will be safe, because there’s no component in the vaccine that hasn’t been in other vaccines before,” he says.
The success may also help bring more funding to malaria vaccine development, which has gotten relatively little support in comparison to other pharmaceutical research. “Before COVID, malaria had been chronically underfunded,” Hill says. “Given the mortality, the investment was very small. All the Big Pharma companies knew that if you made a malaria vaccine, you’d have to sell it for a modest price. There aren’t billions of dollars to be made, because the target countries can’t afford [a] $100 vaccine.” If the vaccine can get closer to 100% efficacy over time, it could help eliminate the billions of dollars spent on bed nets and other interventions.
It’s theoretically possible that the vaccine could be ready in two years, Hill says, since the COVID-19 vaccine was ready in a year and proved that the process could move faster than it ever had before. “We’re talking about things like an emergency use authorization for malaria,” he says. “That’s never happened before, and it rarely happens, except with Ebola, and COVID, and outbreak pathogens. But given that far more people died from malaria in Africa last year than died from COVID, we think that would be reasonable.”
The vaccine could help begin to stop the parasite. “Hopefully what will happen is that in areas that don’t have very much malaria at the moment, you will get close to or actually reach elimination in those countries,” Hill says. “And then malaria will shrink down in its geographic spread as you use the vaccine more and more. There will be fewer deaths. Eventually, we’ll get to the stage where you can get serious about eradication.”