Second malaria vaccine to gain global approval is cheaper and easier to make

The World Health Organization (WHO) has approved a second malaria vaccine to protect children from the deadly disease, which killed 619,000 people in 2021.

Researchers say the vaccine, called R21, is easier to make and cheaper per dose than the first approved malaria vaccine, RTS,S.

“There’s actually enough money to distribute to children,” said Jackie Cook, a malaria researcher at the London School of Hygiene and Tropical Medicine.

R21 met the World Health Organization’s target of 75% efficacy in preventing malaria in a trial of 4,800 children who received three doses of the vaccine before the seasonal peak of malaria. Protection was maintained with a booster dose after 12 months.Data from Phase III trials in Burkina Faso, Kenya, Mali and Tanzania are presented in a preprint1 Released on September 26th.

“By adding vaccines to existing tools, tens of thousands of people will be saved every year,” Mary Hamel, an epidemiologist in charge of WHO’s malaria vaccine implementation program, told a news conference in Geneva, Switzerland. Children’s Lives.” The endorsement was announced on October 2. The WHO recommendations follow discussions last week by the WHO’s Strategic Advisory Group of Experts on Immunization and its Malaria Policy Advisory Group.

The vaccine has been approved in Burkina Faso, Ghana and Nigeria and will be available in mid-2024 at a price of US$2-4 per dose. RTS,S is a drug recommended by the World Health Organization for use in children in 2021, priced at $9.30 per dose.

more supply

RTS,S, marketed as Mosquirix and manufactured by London-based pharmaceutical company GlaxoSmithKline, has vaccinated more than 1.7 million children in Ghana, Kenya and Malawi since 2019. But the vaccine is not available due to limited supply. Failure to meet the need to combat mosquito-borne diseases that kill more than 260,000 African children under the age of 5 each year.

The latest vaccine, a modified version of RTS,S developed by the University of Oxford in the UK, will be produced by the Serum Institute of India in Pune, which says it has the capacity to produce more than 100 million doses per year. “This is a big step forward towards access and adequate supply to meet demand,” Kate O’Brien, director of the Department of Immunization, Vaccines and Biologicals at the World Health Organization in Baltimore, Maryland, told a news conference.

R21 is also given in three doses, with a booster dose given 12 months after the third dose. Both vaccines are made from a “scaffold” of hepatitis B virus surface antigens and malaria antigens. Plasmodium falciparum Parasites.

The structures of the two antigens are different – R21 is more potent and contains 5 micrograms of antigen per dose, while a single dose of RTS,S contains 25 micrograms of antigen.

Needle selection

Each molecule of R21 is fused with a malaria antigen, and one in five molecules in the RTS,S vaccine has one; this gives R21 a more durable immune response, said Adrian Hill, a vaccinologist at the University of Oxford who helped develop R21. .

Hamel said the two vaccines had similar efficacy, about 75%, when given before the peak transmission season. But “the data so far do not allow us to say that one vaccine works better than another,” she added.

Countries will soon have a choice between the two vaccines. Hill said that with its easier-to-make antigen and a cheaper adjuvant called Matrix-M, made by biotech company Novavax of Gaithersburg, Maryland, production of R21 next year will likely be RTS,S 40 times.

Even with these two vaccines, many obstacles remain on the road to a malaria-free world. In some countries where malaria transmission is particularly severe, vaccine coverage for other diseases is low, Cook said. “Ensuring it gets into the arms of enough children to provide protection remains a challenge,” she added.

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