vaccine results raise hopes for mass deployment

A nurse prepares a dose of malaria vaccine at a hospital in Kisumu, Kenya on July 1, 2022.

A booster dose of a new malaria vaccine maintains a high level of protection against the disease, assured an international research team, Thursday September 8 in the journal Lancet Infectious Diseases, raising hopes that this inexpensive vaccine could be produced on a large scale in a few years. This vaccine, developed by scientists at the University of Oxford, could represent a turning point in the fight against the disease, the researchers said. Malaria, a parasitic disease transmitted by mosquitoes, killed 627,000 people – mostly African children – in 2020 alone.

Last year another vaccine, produced by British pharmaceutical giant GSK, became the first malaria vaccine to be recommended for widespread use by the World Health Organization (WHO). It has since been given to more than one million children in Africa. But research has shown that the effectiveness of GSK’s vaccine is around 60% and drops dramatically over time, even with a booster dose. Oxford’s R21/Matrix-M vaccine was found to be 77% effective in preventing malaria, according to a study published last year. This is the first time that a vaccine has exceeded the efficacy target set by the WHO at 75%.

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For the study, 450 children aged 5 to 17 months in Burkina Faso – where malaria accounts for around 22% of all deaths – received three doses in 2019. They were divided into three groups: two received different doses of the Matrix-M adjuvant, a vaccine ingredient patented by Novavax and also used in the American biotechnology company’s Covid-19 vaccine; the third control group received a rabies vaccine.

Before the 2020 rainy season (when malaria cases increase), 409 children returned for a booster shot. For the group that received the highest dose of adjuvant, the effectiveness of the vaccine increased to 80%, according to the results of a phase 2 trial published Thursday. For the lowest dose, the efficacy was 70%. Importantly, one month after receiving the booster, antimalarial antibodies returned to a level similar to that seen after the first doses received a year earlier, according to the study.

200 million doses per year

“It’s fantastic to see such high efficacy after a single booster dose”, welcomed one of the authors of the study, Halidou Tinto, of the Burkina Faso Health Research Institute (IRSS). Mr Tinto, who was involved in the trial of both malaria vaccines, said GSK’s vaccine had an optimal efficacy of around 60%. “I can therefore confirm that R21 [le vaccin d’Oxford] is much more effectivehe said at a press conference.

“We could see a very substantial reduction in this horrible burden of malaria, a reduction in deaths and illnesses in the years to come, certainly by 2030”, said Adrian Hill, a vaccine specialist at Oxford and co-author of the study. According to him, a 70% reduction in malaria deaths could be achievable within that time frame, in part thanks to the large number of vaccine doses that could be produced quickly.

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Oxford has partnered with the world’s largest vaccine maker, the Serum Institute of India. This last “wishes and is able to manufacture 200 million doses per year starting next year”, said Mr. Hill. The 6 to 10 million doses that GSK can produce per year are not “not enough for 40 million children who need four doses in the first year”, he said. And Oxford’s vaccine would likely cost a few dollars per dose, less than half the $9 for GSK’s version, he added.

Results from a phase 3 trial involving 4,800 participants in four countries are expected later this year, which could potentially lead to approval of the vaccine.

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The World with AFP

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