The Malaria Vaccine: Everything You Need To Know
Just in time for World Malaria Day, a pre-print was published in The Lancet on 20th April 2021 has reported an efficacy of 77% for novel malaria vaccine ‘R21’. This is the first candidate to meet, and exceed, the WHO target of 75%. The randomised controlled trial included 450 children in Burkina Faso, West Africa. And, if upcoming larger-scale trials show similar results, hundreds of thousands of lives across the world could be spared. Most of whom would be young children.
What Causes Malaria?
Malaria is caused by a microscopic parasite called a protozoan. Four kinds of protozoan cause malaria in humans, the most common and serious being Plasmodium falciparum. Humans become infected when they are bitten by an infected female Anopheles mosquito. It is the malaria parasite in her salivary glands, which lies ready to be injected into the human when she takes a blood meal.
Once the parasite has made its way into the bloodstream through the bite, they begin their journey to cause harm. The parasite travels to the human’s liver cells and then blood cells. Here, it matures. And the matured parasite is released into the bloodstream periodically, producing the classic malaria symptoms of relapsing fevers, sweats and shakes. Malaria is more common in warmer climates where Anopheles mosquitos thrive, predominantly Sub-Saharan Africa.
In places where malaria infection is common or ‘endemic’ it is possible for humans to become immune after repeated infections. When this happens, mothers can pass on their antibodies to their babies through their shared bloodstream in the womb or through breastfeeding. Sadly, the immunity is only temporary, as these maternal antibodies disappear over time. This means that young children in endemic areas will become vulnerable to infection with malaria after a short time, as they have yet to develop their own immunity.
In 2019, there were an estimated 229 million cases of malaria and 409,000 deaths. 94% of which occur in Africa – and 67% in children under 5 years of age. Urgent deployment of an effective vaccine could dramatically reduce death and disability among children in these endemic areas.
How Does This New Malaria Vaccine Work?
The R21 vaccine, developed by an international research team including the University of Oxford’s Jenner Institute, is a modified version of the existing ‘RTS,S‘ or ‘Mosquirix’ vaccine administered to almost two million children across Malawi, Kenya and Ghana. Both contain a protein produced by the parasite when it enters the human body; stimulating the immune system to create antibodies.
They both contain an ‘adjuvant’ – an ingredient that boosts this immune response. However, R21 has both a higher protein concentration and a cheaper adjuvant. As well as being cheaper to produce, R21’s potential 77% efficacy is currently proving to be much higher than the 56% found in Mosquirix trials.
What Could This Mean For The Future?
Despite decades of international effort against malaria including bednet distribution, insecticide sprays, and innovative new treatments, malaria remains one of the biggest causes of death for children in Africa. The rollout of an effective vaccine could make childhood illness and death from malaria a thing of the past.
Lynsey Bilsland, from Wellcome Trust, who part-funded the trial emphasises the burden of malaria in young people. Regarding the vaccine, she says that “despite global efforts against malaria, too many lives are still lost to this disease, especially babies and young children”. She also expresses optimism in light of the impressive new findings, stating that there is “an extremely positive result showing high efficacy of a safe, low-cost, scalable vaccine designed to reach the huge numbers of children who are most at risk”.
This is all the more important in the context of climate change and global warming. As these are causing vast swathes of land to become hospitable homes to mosquitos. This could spread malaria further around the globe. Including Northern and Central Europe, Australia, North America, and new areas of Asia and Eastern Africa.
What happens now?
Researchers have already commenced recruitment for Phase III trials. These will, hopefully, confirm the vaccine’s efficacy and safety on a much larger scale. Working with 4800 children across four African countries, to be more specific.
Professor Adrian Hill of the Jenner Institute team stated that they will consider applying for WHO approval for emergency use, as they did for the COVID-19 Oxford/AstraZeneca vaccine. “I’m making the argument as forcefully as I can.” He has stated, “because malaria kills a lot more people than COVID in Africa, you should think about emergency use authorisation”. He also compares the urgency with that of the COVID-19 vaccination “They did COVID in months – why shouldn’t they do malaria in a similar length of time?”
Hill estimates that approval for use of the R21 malaria vaccine could be granted as early as the end of 2022.