Positive efficacy results from a late-stage trial of the R21/Matrix-M (R21) malaria vaccine, developed by the University of Oxford and the Serum Institute of India, have been published in The Lancet.
R21, which uses an adjuvant developed by Novavax to boost immune response, became the second malaria vaccine to be prequalified by the World Health Organization’s (WHO) in December 2023, following the organisation’s prequalification of the RTS,S/AS01 vaccine in July 2022.
Malaria, a mosquito-borne disease, is the largest cause of death in young African children, with over 600,000 deaths globally each year.
Despite high demand, WHO outlined that the available supply of RTS,S has been limited and expects the addition of R21 to result in sufficient vaccine supply for children living in areas where malaria is a significant public health risk.
The late-stage trial supporting the use of R21 was conducted across multiple sites in four African countries with more than 4,800 children aged five to 36 months.
According to the newly-published results from the study, trial investigators found on average 78% vaccine efficacy over the first year of follow-up across all sites in children aged five to 17 months – the age range group which is studied for most malaria vaccines.
Efficacy over this period was broadly similar across sites and in different transmission settings, and safety data from the trial showed the vaccine was well tolerated, with injection site pain and fever the most frequent adverse events.
Significantly increased immune responses to R21 and slightly higher vaccine efficacy were observed in the five- to 17-month age group compared to those aged 18 to 36 months, which the University of Oxford said supports planned vaccine deployment initially from five months in African children.
Professor Adrian Hill, chief investigator of the R21/Matrix-M phase 3 trial, said: “The continued high efficacy of this new vaccine in field trials is very encouraging and consistent with the high efficacy and excellent durability observed in a smaller four-year phase 2b trial.
“This data supports an important role for the unique high-density nanoparticle display of the conserved repeat region of the malaria parasite circumsporozoite protein, a feature in the design of the R21 vaccine, in providing such high vaccine efficacy and, thereby, an important new tool for malaria control.”