Malaria Gamechangers, Part 9: RTS,S Malaria Vaccine

Part 9 of our Malaria Gamechangers series (check out Episodes 1-8) highlights the RTS,S/AS01 [RTS,S] malaria vaccine, the first-ever malaria vaccine to receive World Health Organization (WHO) approval for widespread use.

Developed by GSK, RTS,S has already been administered to nearly 1.7 million children through pilots in Kenya, Ghana, and Malawi. The 4-dose vaccine has shown to reduce malaria cases by 40% among young children after four years of follow-up. Another study found that RTS,S is 75% effective in preventing malaria when administered before the rainy season in highly seasonal transmission areas (i.e. West Africa, Sahel region). These rates of efficacy are not insignificant: researchers estimate RTS,S can save 24,000 lives for every 30 million doses administered.  

Gavi, the Vaccine Alliance, has invested over $150 million in the deployment of RTS,S, and has established a funding agreement with GSK and MedAccess to ensure the delivery of 18 million doses by 2025. These doses have already been allocated to 12 African countries, including the pilot countries: Kenya, Ghana, and Malawi. UNICEF is the primary buyer and will work with countries to supply these doses largely through existing national immunization programs, creating a pathway to reach millions of the most at-risk children.   

Since demand far exceeds supply, countries will work with Gavi to prioritize the most vulnerable and high-risk populations, such as children with limited access to malaria prevention services or who live in dense, high-transmission areas. Beyond 2025, RTS,S production is expected to increase to 15 million doses per year thanks to a product transfer deal with Bharat Biotech, of Hyderabad, India. 

I spoke with Dennis Di Mascio, the Malaria Vaccine Program Lead at GSK. You can watch the film and read the full interview below.

Mr. Dawisha: Why is RTS,S a game-changer in the fight against malaria?

Mr. Di Mascio: So, RTS,S is the first vaccine for malaria, and more broadly, any disease caused by a parasite. Today, it remains the only one to be recommended for use in endemic countries. And it’s pre qualified by the WHO.

It’s a game-changer in two senses. Scientifically, it was a big breakthrough, being the first vaccine to demonstrate efficacy against malaria in a large Phase III trial. And it has potential to help preventing one death in 233 cases of malaria for every 200 children fully vaccinated. And this impact on morbidity and mortality could be significant. And it has been a game-changer also in terms of implementation, because the experience of implementing RTS,S in the WHO Malaria Vaccine Implementation Program has shown that it is possible to deliver the vaccine against malaria in multiple doses using the existing platform for immunization. So it added an additional tool to the tool box needed to get ahead of this devastating disease.

Mr. Dawisha: Where has RTS,S been piloted and what are the next steps?

Mr. Di Mascio: So since the start of the malaria vaccine implementation program in 2019, more than 4.5 million doses have been administered, reaching almost 1.5 million children, and this number continues to grow. So earlier this year, Ghana, Kenya, and Malawi – which are the three countries that are part of the implementation program – also decided to enlarge vaccination, reaching more communities with the malaria vaccine.

From a GSK perspective, we are now ramping up our supply, and we are working with partners so that more countries can access the vaccine – so with the support of Gavi and UNICEF at the beginning of 2024. As with other vaccines, it takes time to ramp up supply. And in parallel, we’re also working to transfer the technology to Bharat Biotech of India so that they can produce the antigen and supply the vaccine at scale. We will continue to supply AS01, which is the adjuvant needed to boost the immune system of the individual. And we are working to increase the volume while Bharat is scaling up the antigen manufacturing.

Mr. Dawisha: What would you consider to be the long-term goals of RTS,S and the potential roadblocks along the way?

Mr. Di Mascio: We are really excited to see RTS,S rolled out more broadly, and we will continue to support its supply in the long term, providing the adjuvant. We also see, as a success, the rollout of other malaria vaccines as a long-term goal. We would like to see more vaccines against malaria follow the RTS,S footsteps, and we are proud that RTS,S is a pathfinder – not only on the development side, but also on the policy and financing side of these complex programs.

In terms of roadblocks, it takes coordination – it’s about immunization programs and malaria programs. And so the rollout can be complex, but actually there could be benefits together with challenges of this coordination. The transfer of the technology remains a complex activity, but GSK and Bharat are putting in place the resources to secure this long-term, sustainable approach. And funding to sustain the production of new, innovative vaccines in a low-resource setting can be also challenging, as is the funding for malaria in general.

Mr. Dawisha: Going back to the rollout being complex, I’d like to get your thoughts on the initial rollout phase as you ramp up supply to meet demand.

Mr. Di Mascio: So, basically, there has been extensive work under the leadership of WHO, and WHO developed a framework for the allocation of the limited supply. And so there’s been a  framework with different indicators that has been used to define where the vaccine would be allocated at the beginning, when there is limited supply.

I mentioned this before – it’s not only for malaria, but for other vaccines – the most critical part is the beginning. Because the preparation and the ramp-up of manufacturing, it’s a complex task. And so we have a long-term strategy, which is the transfer to Bharat Biotech to increase the supply. But for the time being, there is a limited supply that is mainly driven by our antigen, which is produced in GSK.

Stay tuned as we highlight more Malaria Gamechangers later this year!