A malaria vaccine candidate that had previously shown great promise in human trials has just successfully passed a new trial stage with over 75% efficacy — meeting the standards imposed by World Health Organization’s Malaria Vaccine Technology Roadmap.

Researchers at the University of Oxford and their collaborators have just released the results of the Phase 2b trial of R21/Matrix-M™, a candidate malaria vaccine, and the data is very encouraging. This compound has previously shown high levels of efficacy in protecting people from the disease. In the previous trial, which focused on West African children in 2021, the compound protected 77% of participants over a 12-month period from the malaria-causing parasite (Plasmodium).

The results of the current trial are similar, with R21/Matrix-M™ showing an efficacy of up to 80%. Such results are very good news, as they place us well on our way toward a viable vaccine against this terrible and pervasive disease.

Predictably preventive

“It is fantastic to see such high efficacy again after a single booster dose of vaccine. We are currently part of a very large phase III trial aimed at licensing this vaccine for widespread use next year,” says Halidou Tinto, Professor in Parasitology, Regional Director of IRSS in Nanoro, and the trial’s Principal Investigator.

Researchers from the University of Oxford and their partners have today reported new findings from their Phase 2b trial following the administration of a booster dose of the candidate malaria vaccine, R21/Matrix-M™ – which previously demonstrated high-level efficacy of 77% over the 12 months following administration in young west African children in 2021.

In their findings (reported in The Lancet Infectious Diseases), they found that a vaccine booster dose at one year following a primary three-dose regime maintained high efficacy against malaria, and continued to meet the World Health Organization’s Malaria Vaccine Technology Roadmap goal of a vaccine with at least 75% efficacy.

The trial worked with 450 participants aged 5 to 17 months in the area of Nanoro, Burkina Faso. They were split among three groups; the first two received R21/Matrix-M with either a low dose or high dose of the Matrix-M adjuvant vaccine as a booster, and the third group received a rabies vaccine (they acted as the control group). All in all, 409 participants received an experimental shot.

Overall, the team reports that the vaccine has an efficacy of 80% in the group that received the higher adjuvant doses, and 70% in the group which received the lower dose; the efficacy was measured by tracking antibody levels in participants 12 months after receiving the shot. No serious adverse effects were noted by the team or the participants following the administering of the vaccine.

“We are delighted to find that a standard four-dose immunisation regime can now, for the first time, reach the high efficacy level over two years that has been an aspirational target for malaria vaccines for so many years,” explains paper co-author Professor Adrian Hill, the University of Oxford’s Director of the Jenner Institute and Lakshmi Mittal and Family Professor of Vaccinology.

Based on these results, the trial has been extended for another two years to allow researchers to assess if further booster doses are needed to maintain the high efficacy seen so far over time. The ongoing Phase III trial will work with 4,800 children aged 5 to 36 months across 4 African countries and its results are expected later this year — results which will doubtlessly help steer the further developmental path of the compound.

The paper “Efficacy and immunogenicity of R21/Matrix-M vaccine against clinical malaria after 2 years’ follow-up in children in Burkina Faso: a phase 1/2b randomised controlled trial” has been published in the journal The Lancet Infectious Diseases.