More than 130 years after the naming of the Plasmodium parasites behind malaria, the world now has its first approved vaccine against them. Many malaria researchers have celebrated the development, but others have expressed concerns over the deployment of a vaccine that has only moderate efficacy.
On 6 October, the World Health Organization (WHO) backed the vaccine — called RTS,S — and recommended its widespread use among children in sub-Saharan Africa, which is home to the deadliest malaria parasite, Plasmodium falciparum.
“The RTS,S malaria vaccine — more than 30 years in the making — changes the course of public health history,” said WHO director-general Tedros Adhanom Ghebreyesus at a press briefing announcing the endorsement.
Nevertheless, one modelling study suggests that it could prevent the deaths of 23,000 children a year, if the full series of doses were given to all kids in countries with a high incidence of malaria2 — making a significant dent in the tremendous toll of the disease, which killed 411,000 people in 2018.
Leaders across Africa are now considering whether and how to deploy the vaccine. In Mali, for example, malaria researcher Alassane Dicko at the University of Bamako told Nature that, soon after the WHO’s announcement, the nation’s minister of health asked him what Mali needed to do to get the vaccine.
“I told her we need to push as a country, at the highest levels of our government, to make this vaccine available at an affordable cost as soon as possible,” he says.
Researchers have been developing and testing the RTS,S vaccine — also known by its brand name, Mosquirix — since 1987, at a cost of more than US$750 million. This was funded mainly by the Bill & Melinda Gates Foundation in Seattle, Washington, and the London-based pharmaceutical firm GlaxoSmithKline (GSK).
Although clinical trials concluded in 2015, the WHO then recommended pilot studies to determine the feasibility and safety of this multi-dose vaccine outside a clinical trial.
Gavi, the Vaccine Alliance, a health partnership based in Geneva, Switzerland, helped to fund the pilot programmes, which have distributed 2.3 million vaccine doses across Ghana, Kenya and Malawi. It reports that in these studies, hospitalizations from severe malaria decreased by about 30%. These results gave the WHO the confidence to recommend that four doses of the vaccine be given to children living in regions with moderate to high levels of malaria transmission.
However, Dicko says countries might achieve even greater drops in hospitalizations and deaths through tailored rollouts.
In August, he and his colleagues published results from a clinical trial finding that the RTS,S vaccine reduced childhood malaria deaths by 73% if children received three doses in the run-up to the rainy season — when malaria peaks — and another dose before the rainy season in the two subsequent years3. Notably, this was done in conjunction with a method called seasonal malaria chemoprevention, in which healthy children take a monthly dose of anti-malaria drugs to help prevent the disease.
In addition to deciding how to deploy the vaccine, countries will need to determine how much it will cost to purchase and distribute it — and whether donors will help to foot the bill.
The vaccine manufacturer GSK released a statement pledging to make 15 million annual doses available at just above the cost of production. However, roughly 100 million doses will be needed annually if all children in high burden countries are to receive the shots2.
Might existing measures be overshadowed?
Some researchers fear that the excitement over a vaccine will overshadow existing malaria control measures that are already often underfunded, including insecticide programmes and functional health systems.
At a potential cost of about $5 per dose, researchers suggest the vaccine rollout, including its distribution, would cost around $325 million to administer each year across ten African countries with a high incidence of malaria. They point out that in some of these countries, other malaria measures have faltered because of a lack of support.
“I respect the researchers involved with this massive effort, but the reality is that so much money has been poured into this vaccine, even when the results from studies are disappointing,” says Badara Cisse, a malaria researcher at the Institute for Health Research, Epidemiological Surveillance and Training in Dakar. “I don’t think a 30% effective vaccine would be acceptable for Americans.”
Still, he and James Tibenderana, a Ugandan epidemiologist at the Malaria Consortium in London, say the RTS,S vaccine could be impactful in some regions. To achieve that, Tibenderana stresses the need for extensive communication campaigns, so that misinformation doesn’t hamper the rollout.
“People will wonder why a 30-year-old, partially effective vaccine is suddenly being introduced during a pandemic — and targeted only at Africans,” he says. “The misinformation around COVID-19 vaccines should teach us that we can’t take community trust for granted.”
Despite the long road ahead, he and others are grateful for the WHO’s decision. “With the devastation of COVID-19, and with progress stalled on malaria control, and news of resistance to anti-malaria drugs, it’s uplifting to see some positive news,” he says.