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. 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. Halidou Tinto, Professor in Parasitology, Regional Director of IRSS in Nanoro, and the trial Principal Investigator, said:‘It is fantastic so see such high efficacy again after a single booster dose of vaccine.
