Dial M for malaria
New tools for tackling malaria are arriving, including an exciting new vaccine. But will the world pay for them?
Malaria has been a deadly scourge that has stalked humanity for millennia. This parasitic disease is recorded in the oldest medical texts, tracing back through Sumerian, Egyptian, and Chinese writings nearly 5,000 years ago. It has driven the evolution of genetic traits like sickle cell anemia as our ancestors adapted to survive its onslaught. But now, after decades of scientific struggle, we finally have powerful new weapons to turn the tide against this formidable enemy.
Malaria is a parasitic infection transmitted by mosquitoes and is responsible for nearly 95% of malaria cases and deaths in Africa. The disease is particularly lethal for children under the age of five, with nearly 600,000 children succumbing to it annually. Despite being treatable, the infection must be identified and treated quickly, which is challenging in many of Africa's remote rural areas.The journey to develop a malaria vaccine has been long and arduous.
Several factors have contributed to the delay. Firstly, malaria is a complex disease caused by a parasite, which is more challenging to target with a vaccine compared to viruses or bacteria. The parasite has a complicated life cycle, involving multiple stages in both the mosquito and human hosts, making it difficult to develop a vaccine that can effectively target all stages.
Additionally, the financial and logistical challenges of developing a vaccine for a disease that predominantly affects low-income countries have been significant. Pharmaceutical companies have historically been reluctant to invest in research and development for diseases that do not promise substantial financial returns. However, the global health community has recognized the critical need for a malaria vaccine, leading to increased funding and collaborative efforts to overcome these challenges.
Two groundbreaking malaria vaccines have arrived, with the most recent one reaching Africa at the end of May. The first vaccine, RTS,S (Mosquirix), was approved by the WHO in 2021 after a long and arduous development process with support from international donors. Despite its supply constraints and high cost, RTS,S marked a significant milestone.
The real game-changer, however, is the R21/Matrix-M vaccine, developed by the University of Oxford and the Serum Institute of India. The Serum Institute already has the capacity to produce 100 million doses annually and has manufactured 25 million doses at risk, at just $3.90 per dose – a fraction of the cost of RTS,S. This significant investment by the Serum Institute, including funding the phase 3 trials and building the production plant at their own risk, is likely to play a crucial role in the fight against malaria.
R21 is not the vaccine that the world will use to eliminate malaria. For that further improvements will be needed. Normally, vaccines work by training the immune system to recognise antigens—typically proteins—that are found on the surface of the infectious agent. But targeting such proteins on the Plasmodium parasite that causes malaria has proven difficult as it has a multi-stage life cycle, which presents different antigens at different stages, making it harder to pick the best target. R21 works at the stage immediately after a person is bitten. At this point a few dozen sporozites of a parasitic protozoan known as Plasmodium faliciparum travels through the blood stream and make their way to the liver. R21 (and RTS,S) make antibodies that attempt to stop these sporozites enter the liver.
But vaccines that will help the world eliminate malaria will need to be better, and combine vaccines that work on other stages of the malaria life cycle. Work is under way on a blood stage vaccine—when the parasite infects blood cells. Trials of a combination of R21 and a blood stage vaccine could come within three years. The ultimate goal, though, would be to add a transmission blocking vaccine as well. The ready supply of R21, and a willing manufacturer, means that improved combination vaccines for trials are more easily within reach.
In the meantime, the new vaccines, combined with better bednets and other innovations, can help reduce the prevalence of the disease and save many lives. One estimate suggests that for every 200 children vaccinated, a life will be saved. Both rich and poor countries must invest in controlling this disease, which imposes a staggering human and economic burden, costing an estimated $16 billion in lost GDP annually1.
Over the rest of the decade, the world needs to go on the offensive against malaria. That means investing properly in malaria control of all kinds, including vaccines. Not only will the number of human lives saved be enormous, but the economic returns on investment will also be substantial, benefiting households and entire economies. With renewed investment, ambition, and a good strategy, we can envision a future where this ancient plague is finally defeated, consigned to the history books alongside other scourges humanity has overcome.
For further reading see:
New fronts are opening in the war against malaria. The Economist, May 30th 2024 (by Liam Taylor & Natasha Loder)
Why developing the world’s first malaria vaccine has taken so long. The Economist, July 18th 2023 (by Olivia Prowse & Natasha Loder)
X-thread on the new vaccine
The Intelligence podcast, June 12th. Second segment
https://x.com/louie_freeman1/status/1800506309399454026