On Sept. 8, 2022, researchers from the University of Oxford and their partners reported 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 following 12 months 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 authors report from a Phase IIb randomised, controlled, double-blind trial conducted at the Clinical Research Unit of Nanoro (CRUN) / Institut de Recherche en Sciences de la Santé (IRSS), Burkina Faso. A total of 450 participants aged five to 17 months were recruited from the catchment area of Nanoro, with 409 receiving the booster.

The participants were randomly assigned to three groups, with the first two groups receiving the R21/Matrix-M (with either a low dose or high dose of the Matrix-M adjuvant) vaccine as a booster and the third a rabies vaccine as the control group. Each child received the same booster vaccination as their primary series of vaccinations. Doses were administered in June 2020, largely prior to the peak malaria season.

The researchers report a vaccine efficacy of 80% in the higher-dose adjuvant group, and 70% in the lower dose adjuvant group, over 12 months of follow-up. Antibody levels were restored to similar levels as those following the primary vaccinations 28 days after the booster doses were administered. No serious adverse events related to the vaccine were noted.