The WHO has officially recommended a second malaria vaccine for children, the R21/Matrix-M, co-developed by researchers at Oxford University and the Serum Institute of India. Global rollout could greatly improve access to immnization against a disease that kills over 600,000 people a year, 96% in Africa.  But experts stress that vaccines can complement — but not replace — other malaria control strategies.

Nearly two years after the World Health Organisation (WHO) officially recommended the RTS,S malaria vaccine, the global health body on Monday approved a second vaccine, the R21/Matrix-M – whose clinical trial results have shown a high degree of efficacy in preventing serious malaria cases and deaths amongst children at risk. 

The WHO decision paves the way for a global rollout of a vaccine that could make a significant dent in the burden of malaria today – which mostly kills African children under the age of 5.

“The R21/Matrix-M malaria vaccine is an easily deployable vaccine that can be manufactured at mass scale and modest cost, enabling as many as hundreds of millions of doses to be supplied to countries which are suffering a significant malaria burden,” said the University of Oxford in press release. The Serum Institute of India has “already established production capacity for 100 million doses per annum, which will be doubled over the next two years.”

Speaking at a WHO press briefing, Dr Tedros Adhanom Ghebreyesus, WHO Director-General, noted that just as COVID-19 vaccines played important roles in getting the pandemic under control, RTS,S and R21/Matrix-M vaccines — which he described as safe and effective — are also giving the world new hope of bringing malaria, which is one of the oldest diseases known to humanity, under control.

The global health organisation’s recommendation was based on advice from two expert groups — the Strategic Advisory Group of Experts on immunisation (SAGE) and the Malaria Policy Advisory Group.

“Both groups reviewed evidence from the trials of the R21/Matrix-M vaccine, which showed that in areas with seasonal transmission, it reduced intermittent cases of malaria by 75% in the 12 months following a three-dose series of the vaccine; a fourth dose given a year after the third was shown to maintain protection,” the WHO Director General said.

When used in real-life settings in peak malaria season, both R21/Matrix-M and the RTS,S appear to perform similarly, he added, saying “It’s comparable with other recommended malaria interventions.”

While the Phase 3 clinical trials have shown the vaccine to be safe, safety monitoring will continue as the vaccine is rolled out on a wider said.

At a cost of between two and four US dollars a dose, the cost of the new vaccine is similar to that of the RTS,S. 

Reshaping the fight against malaria

Welcoming the development, Gavi, The Vaccine Alliance said the vaccine can help reshape the fight against malaria, a disease that killed 619,000 people globally in 2021 with 96% of those deaths being in the Africa region, thus making the disease one of Africa’s biggest killers.

David Marlow, CEO of Gavi, described the announcement as another major step towards our goal of creating a malaria-free life for every child. The vaccine, along with the existing RTS,S vaccine, “will be an effective complement to existing malaria interventions.

The vaccine can “play a key role in meeting the high demand we are seeing in endemic countries,” Marlow added. 

Since 2000, malaria deaths have fallen by more than half, and the disease has been successfully eliminated from many parts of the world. But globally, progress has stalled with nearly half the world’s population remaining at risk of malaria. In 2021, there were an estimated 247 million cases of malaria, and 619,000 deaths with 95% of cases and deaths being in Africa — and mostly among children under five. 

Demand for the RTS,S vaccine far exceeds supply thus making the R21/Matrix-M vaccine a particularly important additional tool to protect more children faster, and to bring the world closer to the WHO’s vision of a “malaria-free world”, noted Tedros at the press briefing. 

Already being licensed in West Africa

The R21/Matrix-M malaria vaccine has already been licensed for use in Ghana, Nigeria and Burkina Faso – which opted to go ahead with deployment even before the formal WHO greenlight based on previously reported clinical trial results. 

“The R21/Matrix-M malaria vaccine has been shown to be safe and highly effective across multiple clinical studies and is now approved as WHO policy for widespread use. The vaccine is easily deployable, cost effective and affordable, ready for distribution in areas where it is needed most, with the potential to save hundreds of thousands of lives a year,” said Sir Adrian Hill, Director of Oxford’s Jenner Institute, where the vaccine was developed.

According to the institute, the vaccine recently reached the primary one-year endpoint in a pivotal large-scale Phase III clinical trial that included 4,800 children across Burkina Faso, Kenya, Mali and Tanzania. 

“The Phase III trial results are under peer review before publication,” the institute stated in its press release coinciding with the WHO announcement.

While the vaccine had a 75% efficacy when given just before high transmission season, WHO said, it had some waning of efficacy over the first year of follow-up at both seasonal and perennial transmission sites. But a booster dose restored efficacy at the seasonal sites with a vaccine efficacy over 18 months of 74%. 

An earlier Phase IIb clinical trial conducted in Burkina Faso also reported two-year efficacy and showed that a booster dose of the vaccine maintained high efficacy against malaria, meeting WHO’s Malaria Vaccine Technology Roadmap goal of a vaccine with at least 75% efficacy.

There has been some speculation over whether the new Oxford vaccine could ultimately be more effective than its predecessor.  However WHO said that experience to date shows similar performance in settings with high seasonal malaria transmission:

“The two WHO-recommended vaccines, R21 and RTS,S, have not been tested in a head-to-head trial,” WHO notedin a press release.  “There is no evidence to date showing one vaccine performs better than the other. The choice of product to be used in a country should be based on programmatic characteristics, vaccine supply, and vaccine affordability.”

Closing the gap between supply and demand

Speaking at the briefing, Dr Hanna Nohynek, Chair of SAGE, said malaria vaccines introduced widely have the potential to save tens of thousands of young lives each year. She added that the introduction of the vaccine should be done in the context of comprehensive malaria control efforts, and the vaccine can be used following a seasonal or age-based schedule as already described for RTS,S. 

“The availability of a second malaria vaccine is expected to close the gap between supply and demand, enabling broader and possibly unconstrained access,” the chair said.

Meanwhile, Serum Institute of India  said its doses are ready for wider roll-out almost immediately, with an expected production capacity of over 180 million doses per year. SII also confirmed it is collaborating with DEK Vaccines in Ghana to develop capacity to undertake fill-finish manufacturing in the country.

“The WHO recommendation and approval of the R21/Matrix-M vaccine marks a huge milestone on our journey to combat this life-threatening disease, showing what exactly can be achieved when the public and private sector, scientists and researchers, all work together towards a shared goal,” said Adar Poonawalla, CEO of the Serum Institute of India.

No silver bullet to end malaria

While commending the addition of the new vaccine to available malaria-control tools, there is no silver bullet to end the disease, Dr Michael Charles, CEO of the Roll Back Malaria Partnership noted.

“While this announcement is a step in the right direction, there are still major hurdles to overcome,” he said. “In the face of significant funding shortfalls and the growing threats of insecticide and drug resistance, and climate change – further investment must be urgently mobilised to scale-up, manufacture and roll-out malaria vaccines to ensure they are readily accessible to countries that decide to use them.” .

With countries facing different challenges, health ministries will need to determine how the two vaccines can complement their existing malaria control strategies. 

“This new vaccine will be highly effective to fight malaria, but must be used in tandem with other tools such as insecticide-treated nets, indoor residual spraying and preventive medicines to have the greatest impact,” Charles added.

Image Credits: Tom Wilkinson,/Oxford University, University of Oxford/Tom Wilkinson.