Could a new malaria jab really finish off the disease? Researchers at GSK have high hopes

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02-05-2025

A groundbreaking new malaria vaccine that could be three times more effective than existing jabs is under development by scientists at GSK, the Telegraph can reveal.
The product, earmarked for roll-out in 2035, will target both liver and blood-stages of malaria and aims to offer 90 per cent protection against the notoriously difficult to control parasite, which is carried and transmitted via mosquitoes.
Development work is being led by Dr Katie Ewer, the British scientist formerly of Oxford University's Jenner Institute who helped spearhead AstraZeneca's Covid-19 vaccine, one of the most widely distributed jabs during the pandemic.
'Malaria is a tough pathogen. It's taken 35 years to even get to the point where vaccines are available,' Dr Ewer told The Telegraph. 'Now we're building on that technology and aiming for higher efficacy and longer-lasting protection with the second-generation version. It's a really exciting time.'
But it's not the first time bold claims have been made over malaria vaccines and their potential to change the tide against the notorious mosquito-borne disease that continues to kill 600,000 children every year, mostly in Africa.
The first-generation jabs – GSK's product the RTS,S and a sister version, R21,developed by Dr Ewer's former team at the Jenner Institute – were both rolled out for the first time in sub-Saharan Africa last year, but have not been the silver-bullet many in the global health space had hoped for.
Initially claiming to be up to 70 per cent efficacious, data from the field suggests the protection they offer is in fact much lower – around 30 per cent – and that the immune response wanes over time.
'We have a dilemma where in the context of vaccines, the malaria jabs aren't very good. We think they only provide between 30-50 per cent protection,' Chris Drakeley, professor of Infection and Immunity at the London School of Hygiene and Tropical Medicine told The Telegraph.
Dr Ewer's team are aiming to address some of the pitfalls of the R21 and RTS,S with their new product by targeting the malaria parasite at an additional stage of its life cycle.
The existing malaria vaccines work by killing off the parasites in the liver, the first stage of a malaria infection. There, the parasites undergo a development process and rapidly multiply before releasing into the bloodstream, the point at which a person becomes sick.
The new jabs will not only target the liver-stage, but also have the ability to kill any parasites that have slipped through the net into the blood – providing a backstop to ensure that all the microorganisms have been killed.
'The problem with the current vaccines is that you need to kill every single damn parasite in order to get protection, and if just a very tiny number, one or two or three of these parasites escape, over time, they will build up in the blood and the kids will still get sick,' said Prof Eleanor Riley, professor of Immunology at the University of Edinburgh.
'There's been a growing consensus over the last five to 10 years that single stage liver vaccines wouldn't be enough, and that's partly reflecting our increased knowledge of the parasite itself,' Dr Ewer said. 'By adding in a blood stage, we hope that we can give an extra layer of immunity so that the parasites that are missed at the liver stage can be blocked,' she added.
'The reason for combining the two vaccines is that neither offers very high protection on its own – and they work in completely different ways,' said Prof Riley.
'One targets the parasite in the liver, while the other attacks it in the blood. So, there's potential for an additive or even synergistic effect.
'For example, if the liver-stage vaccine reduces the number of parasites by 90 per cent, and the blood-stage vaccine also reduces what's left by 90 per cent, together they could achieve around 99 per cent effectiveness. That's the idea behind combining them,' Prof Riley explained.
Malaria costs the global economy over $12 billion annually; if these vaccines are able to provide a far better level of protection against malaria than the current jabs, it may seem puzzling why their rollout could still be a decade away.
But the timeline is in fact typical – and even quick – particularly in the context of malaria.
More than 200 malaria vaccines have been tried and tested since the early 1990s, and none have worked until the R21 and RTS,S – both of which were only approved in 2024.
The team at GSK are still in the discovery phase, meaning they are yet to select a candidate vaccine that can be taken forward to testing. It typically takes between 10 to 15 years or more to complete all three phases of clinical trials for any new drug before it can be licenced for use.
Another major part of the challenge is the pathogen itself: malaria is caused by a complex parasite, as opposed to a virus or bacteria, that is highly adapted and is notoriously good at evading the immune system.
'The malaria parasite has 4,000 to 5,000 genes, compared to a virus like Covid, which only has a few – some of which are on the surface and easier to target. With malaria, there are thousands of possible targets for a vaccine, so scientists have to carefully choose which ones to focus on,' Dr Ewer explained.
'The other challenge is that most vaccines work by copying the body's natural immune response. But with malaria, that doesn't work well because natural immunity takes years to build up and doesn't last long. Our immune systems just aren't very good at fighting malaria on their own,' she added.
And despite much of the technology behind liver and blood-stage malaria vaccines already existing, combining the two has proven to be a complex challenge – one that many research groups have attempted without success.
A USAID-funded research project led by Simon Draper, a former colleague of Dr Ewer at Oxford, produced promising data from a trial in Burkina Faso, that found blood-stage malaria vaccines to be effective in humans for the first time in 2024.
The team had planned to combine blood- and liver-stage components later this year, but their progress was abruptly halted and US overseas aid funding was suspended by the Trump administration.
'Earlier attempts to make combined vaccines using blood-stage antigens often failed because of something called 'immune interference.' This happens when the immune system focuses on one part of the vaccine, but that response interferes with or weakens the response to other important parts.
'It's not just 'shove it all in together and it should be fine'. It's a lot more nuanced,' Dr Ewer said.
'And it's not just about science – we also need to be able to manufacture millions of doses at an affordable cost. So whatever we develop has to be effective and easy to manufacture at scale,' she added.
'The current vaccines we have were a major milestone, but they're not as effective as we'd like them to be, and so second generation vaccines are super important. What GSK is doing in terms of combining the vaccines is really exciting, and if you can get 90 per cent effectiveness you are moving towards an elimination tool,' Lottie Renwick, head of strategy and policy at the charity Malaria No More UK, told The Telegraph.
'But malaria is so complicated and you're still going to need your toolbox of interventions no matter what – including bed nets, drugs, and indoor residual spraying,' she added.
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