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[OUAGADOUGOU] Researchers plan to launch a new malaria vaccine next year after tests in children in West Africa showed it to be up to 80% effective.
More than 100 malaria vaccine candidates have been tested in humans over the last few decades, but none had previously reached the World Organization’s goal of more than 75% efficacy in health.
Scientists have warned that progress has stalled in the fight against this mosquito-borne disease, which has caused more than 640,000 deaths in 2020, most of them children in sub-Saharan Africa.
“Conducting vaccine trials in Africa assures us that the efficacy of a candidate vaccine at the end of the trial will reflect its performance under real-world conditions of use”
Halidou Tinto, IRSS, Burkina Faso
Researchers from the University of Oxford (UK) and the Institut de recherche en sciences de la santé (IRSS) de Nanoro in Burkina Faso say that a booster injection of the malaria vaccine candidate, called R21, showed effective efficacy. 80% in children who received the highest dose one year after an initial three-dose treatment.
The 78% efficacy was maintained for two years after the booster was given in the trial involving 450 children aged five to 17 months in the Nanoro Clinical Research Unit. There were no serious side effects, the researchers say.
Halidou Tinto, regional director of the IRSS, professor of parasitology and principal investigator of the trial, confided to SciDev.Net that “this is another first in the history of malaria vaccine research. »
“This means that we can maintain an efficacy of more than 75% in the long term if we give a booster dose and this should allow children living in regions where malaria is endemic, such as Burkina Faso, to be very well protected against malaria. at the age they are born. they are the most vulnerable,” she adds.
The vaccine, which Halidou Tinto describes as an improved version of the RTS,S vaccine that is being rolled out in several African countries, had already shown 77% efficacy in the first year in an earlier trial in 2021.
The phase two trial was extended for two years to see if additional booster doses are needed to maintain this high efficacy over time.
The Burkinabe researcher says he is “optimistic” that the latest results can also be replicated in an ongoing phase three trial involving 4,800 children in Burkina Faso, Mali, Kenya and Tanzania. The results are expected by the end of this year.
Deployment in 2023
The R21 vaccine, developed at the Jenner Institute of the University of Oxford, is authorized for production by the Serum Institute of India (II).
“We are already planning, in collaboration with our partners (…) to undertake from 2023 a programmatic deployment of R21 in a population of at least 250,000 children in Burkina Faso to accelerate the schedule of large-scale deployment of this vaccine in Africa”, says Halidou Tinto.
It adds that SII had committed to producing at least 100 to 200 million doses of the R21 vaccine per year subject to the WHO issuing a recommendation for its deployment.
“This will complement the only vaccine currently recommended by the WHO (RTS,S) whose current production capacity cannot meet global demand,” says the researcher.
RTS,S, the world’s first malaria vaccine, was recommended by the WHO in October 2021 for use in at-risk children in sub-Saharan Africa and other areas with moderate to high transmission of malaria caused by the Plasmodium falciparum parasite.
However, scientists have emphasized the need for further vaccine development and investment in research.
The director of the Jenner Institute, Adrian Hill, co-author of the study on R21 published in the Lancet Infectious Diseases says it’s “the best data yet” for any malaria vaccine.
“We are delighted to see that a standard four-dose vaccination regimen can now, for the first time, achieve the high level of efficacy over two years that has been an ambitious goal for malaria vaccines for so many years.”
Adrian Hill also says that this vaccine would provide “lasting protection” to the most important group that needs it: young African children. But he points out that the 77% accuracy of the vaccine depended on other control measures such as insecticides and mosquito nets, which should continue to be used.
“Scientifically speaking, it can be said that RTS,S suffered from a saturation of the immune response induced by an excess of hepatitis B virus surface antigens. It is on the basis of this observation that Professor Adrian Hill’s team proceeded with a simplification of the constitution of RTS,S by reducing the amount of HBs antigen, which allows a better immune response against the parasite”, compares Halidou Tinto.
According to their explanations, another “important” change is the use, for R21, of a different adjuvant than the one that had been used in the development of RTS,S
Efficiency in real conditions
James Tibenderana, who will assume the general direction of the non-profit organization malaria consortium in October 2022, called the results of these trials “remarkable”.
Tibenderana, who was not involved in the R21 trials, said the rapid development and deployment of COVID-19 vaccines has shown that it is possible to shorten the time to develop and distribute vaccines while mitigating risks. .
“I hope that these findings will motivate further and sustained investment in research and development of malaria vaccines and their equitable access, as they prevent malaria infections and save lives,” he says.
On a completely different level, Halidou Tinto recalls that malaria is more prevalent in Africa than anywhere else and that it is therefore polite to seek solutions to this disease on African soil.
“On a purely scientific level, conducting vaccine trials in Africa assures us that the efficacy of a candidate vaccine at the end of the trial will reflect its performance under the actual conditions of its use and that it will not be different due to variability in the epidemiological facies or the genetic diversity of malaria parasites”, says the researcher.
He concludes by saying that carrying out these trials in Africa also contributes to developing the capacity of research institutions on the continent through training, as well as that of pharmaceutical regulatory authorities that “will be more efficient.”