A new study published in The Lancet finds that a single dose of the malaria vaccine RTS,S/AS01 reduces severe malaria cases by 30% in young children over four years, offering the first long-term evidence of its real-world impact in high-risk regions.
Key Findings
- A randomized controlled trial involving 12,000 children across four African countries showed the vaccine cut severe malaria by 30% compared to a control group.
- Protection lasted at least four years, with no significant safety concerns beyond minor reactions at the injection site.
- Researchers say the results justify broader rollout, though cost and logistical hurdles remain.
Why the Results Matter
Malaria kills more than 600,000 people annually, mostly children under five in sub-Saharan Africa. Previous trials had shown the vaccine’s short-term efficacy, but this study—conducted in Ghana, Kenya, Malawi, and Tanzania—is the first to demonstrate lasting protection in real-world settings. The World Health Organization recommended RTS,S in 2021 for pilot programs, but uptake has been slow due to its price (around $5 per dose) and the need for multiple administrations.
“This is the first time we’ve seen such durable protection in a high-transmission setting,” said Dr. Brian Greenwood, a malaria researcher at the London School of Hygiene & Tropical Medicine and a study co-author. “It’s a game-changer for countries where healthcare systems are stretched thin.”
How the Study Worked
The trial followed children from ages 5 to 17 months, with half receiving the vaccine and half a control injection. Researchers tracked malaria cases over four years, adjusting for seasonal variations and local treatment practices. The vaccine’s effectiveness held steady even as children grew older, though protection against mild malaria cases was lower (around 20%).
“The durability is encouraging, but we’re still far from herd immunity,” noted Dr. Charles Chanda, a pediatrician at Malawi’s Queen Elizabeth Central Hospital, who was not involved in the study. “We need to pair this with insecticide-treated bednets and rapid diagnostic tests to maximize impact.”
Limitations and Unanswered Questions
The study had key gaps. First, it did not test the vaccine’s effect on Plasmodium vivax, a malaria parasite common in some regions. Second, the trial excluded children under 5 months and those with severe malnutrition, limiting generalizability. Finally, while the vaccine reduced severe cases, it did not eliminate them entirely—highlighting the need for complementary prevention strategies.
“We’re not at the point where we can declare victory,” said Dr. Greenwood. “But these results give us confidence that RTS,S can be part of a larger toolkit to reduce malaria deaths.”
What’s Next for the Vaccine
Health officials are reviewing the data to inform expanded rollout plans. The Global Fund to Fight AIDS, Tuberculosis and Malaria has pledged $150 million to support vaccine distribution in high-burden countries, but scaling up will require partnerships with manufacturers to lower costs. The WHO is expected to issue updated guidance by mid-2024, potentially recommending broader use in children under 5.
In the meantime, researchers are testing next-generation malaria vaccines, including those targeting multiple parasite stages. “RTS,S is a critical step, but we need more options,” said Dr. Greenwood. “The goal remains eliminating malaria entirely.”
