Ghana and Nigeria each approved a new malaria vaccine this month — an important step in the fight against a disease that kills more than 600,000 people annually.

At least 10 other African countries are reviewing trial data for the shot, according to the World Health Organization, so more approvals are expected in the coming weeks.

The vaccine, developed by researchers at Oxford University, is the second to become publicly available. The first, a shot called Mosquirix from drugmaker GSK, has been administered through a pilot program in Kenya, Ghana and Malawi since 2019 but is still in limited supply.

The new vaccine is the first malaria shot to be approved in Nigeria, whose deaths from the disease make up 31% of the worldwide total.

"It’s good news," said Dyann Wirth, an infectious diseases professor at the Harvard T.H. Chan School of Public Health, adding, "These vaccines can save lives and save hospitalizations, reduce the impact of the disease in the most vulnerable young children."

An estimated 619,000 people died of malaria in 2021, the latest annual total available, and 96% of those deaths occurred in Africa, according to the WHO. The disease is caused by a parasite that spreads to humans through mosquito bites.

Scientists have been researching possible malaria vaccines since the 1960s; Mosquirix took more than 30 years to develop and test. To prevent infection, countries with high rates of malaria mostly rely on mosquito nets, insecticides or antimalarial drugs for children.

Next steps for the new malaria shot

The Oxford vaccine consists of three doses administered every four weeks, followed by a fourth dose a year later. So far, the only peer-reviewed data on it comes from a small trial of 450 infants up to 17 months old in Burkina Faso. Among that group, the shot was found to reduce the risk of malaria by 77%.

Adrian Hill, the vaccine’s lead developer and co-director of the Oxford Martin Program on Vaccines, said a Phase 3 trial of 4,800 children up to 3 years old showed similar safety and efficacy. But those findings have not been published in a peer-reviewed journal.

The WHO is still evaluating data on the Oxford vaccine and has not yet recommended it for use. Countries without their own regulatory processes for approving vaccines often defer to the WHO’s recommendations, Wirth said, so they may still wait for that.

The WHO said it does not have a specific timeline for its decision.

"Sadly, we’re not seeing the urgency that WHO and every other regulator in the planet showed with Covid," Hill said, "which is disappointing, given that there are huge numbers of deaths from malaria in young children in Africa."

The new vaccine could reach more people more quickly

The WHO's recommendation of Mosquirix in 2021 represented a major milestone, but manufacturing challenges have led to a slow rollout.

In 2015, GSK closed the Belgium plant where the vaccine was produced, and it did not reopen until 2019. Last year was the first in which the plant continuously manufactured the vaccine’s antigen — the component that stimulates an immune response.

GSK has asked a company in India, Bharat Biotech, to produce the antigen instead, but that won't happen until 2028.

To date, 1.5 million children have received the Mosquirix shot, according to the WHO. In addition to the three countries already administering it, 11 others have applied to receive doses, the WHO said.

"The demand for this vaccine has been unprecedented, with 29 countries already coming forward to Gavi saying that they would like to introduce this vaccine already," Dr. Mary Hamel, the WHO's team lead for malaria vaccines, said on a Wednesday press call. (Gavi is an international vaccine alliance that partners with the WHO, governments and non-profits.)

"Demand far outstrips the supply that’s currently available," Hamel added.

GSK said it expects to have around 4 million doses available later this year, and a total of 18 million by the end of 2025.

But the WHO estimates that 80 to 100 million annual vaccine doses are required to immunize children at risk of malaria.

The Oxford vaccine could help alleviate the shortage. The Serum Institute of India has already committed to producing 20 million doses in the next two months. (The company is manufacturing the doses “at risk,” meaning it hasn’t made a deal with a buyer yet.)

The Oxford shot is also cheaper, at $3 per dose relative to around $10 for the GSK shot.

How do the two malaria shots compare?

Like the Oxford vaccine, Mosquirix consists of four doses. The first three are administered monthly, starting when an infant is 5 months old, followed by the fourth once they reach 15 to 18 months.

In a large-scale trial, three doses of the vaccine reduced the risk of malaria in children by 28% after four years, while four doses had a slightly higher efficacy of 36%.

Hill said the Oxford vaccine's efficacy also wanes over time but was "still very high" after at least 3 1/2 years.

It's possible, though, that the Oxford shot will prove less effective outside of a trial setting, Wirth said, since the study in Burkina Faso largely administered vaccines before the seasonal peak in malaria transmission, which comes in July.

“I expect that, when released at large scale, it will have a similar efficacy to the existing recommended vaccine,” she said.

Neither vaccine will eliminate the need for additional measures to keep malaria from spreading, Wirth added.

“Is it a magic bullet? Will the vaccine alleviate the need for bed nets or insecticide spraying? No, definitely not,” she said. “The vaccine will also not replace the need for drugs, but it can be added to the existing tools to have greater impact.”