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expert reaction to phase 2b study looking at efficacy and immunogenicity after a booster dose of the R21 malaria vaccine candidate in children in Burkina Faso

Results of the phase 2b trial following the administration of a booster dose of the candidate malaria vaccine, R21, in African children have been published in the Lancet Infectious Diseases.

This Roundup accompanied an SMC Briefing.


Prof Sir Brian Greenwood, Professor of Tropical Medicine, London School of Hygiene & Tropical Medicine, said:

“The paper in Lancet Infectious Diseases by Datoo et al. reports over 70% protection against clinical episodes of malaria in Burkinabe children over a two-year period following three priming doses of the R21 malaria vaccine, given in early life, followed by a booster dose of vaccine given just prior to the malaria transmission season, an important finding.  The trial did not include a group of children who received just the priming doses of vaccine, so it is not possible to deduce from this paper how necessary booster doses of the R21 vaccine are to sustain protection over the first five or more years of life during which children are still at high risk of malaria in many seasonal transmission areas.  However, the marked decline in anti-CSP antibody titre in the months after priming, as seen with the RTS,S/AS01 vaccine, and the evidence presented in this and other studies that anti-CSP antibody titre is associated with protection, suggests that booster doses are likely to be needed to sustain protection.”


Prof Azra Ghani, Chair in Infectious Disease Epidemiology, Imperial College London, said:

“Despite ongoing efforts to reduce the malaria burden – including through the provision of insecticide-treated bed nets, improvement in access to treatment, and chemoprevention — malaria continues to pose an unacceptably high burden, resulting in over 640,000 deaths globally each year, mostly in young children in Africa.  These new results demonstrating high sustained efficacy of the R21 malaria vaccine over a 2-year period are therefore very welcome.

“What is particularly encouraging from a scientific perspective are two pieces of information provided by these results; first the demonstration that antibody titres can be restored through boosting with this vaccine, and second that the antibody titres correlate with protection against clinical disease.  Taken together these indicate that similar levels of vaccine efficacy may well be achievable outside the highly seasonal setting in which this particular trial was conducted.  Such trials are currently underway as part of the wider Phase III study and results should be available later in the year.

“These results come at a time at which the fight against malaria is at a crossroads.  With the right investment – notably continued support for The Global Fund to Fight AIDS, TB and Malaria at their upcoming replenishment conference later this month – we can reverse recent trends and continue on the path to elimination of malaria.  Without this investment, we risk losing the gains that have been made over the last decades and witnessing a rising tide of malaria resurgence.” 



‘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’ by Mehreen S Datoo et al. was published in the Lancet Infectious Diseases at 23:30 UK time on Wednesday 7 September 2022.

DOI: 10.1016/S1473-3099(22)00442-X



Declared interests

Prof Sir Brian Greenwood: “My conflicts of interests are (a) being an investigator in the phase 3 R21 trial ongoing in Burkina Faso, Mali and other countries and (b) receipt by my host institution of grants from UKRI and PATH to support evaluation of seasonal vaccination with the RTS,S vaccine.”

Prof Azra Ghani: “Disclosures: 

  • Funding for malaria-related research from the Wellcome Trust, Bill and Melinda Gates Foundation, NIH and The Global Fund.
  • Academic collaboration with the authors of this paper for further analyses of these and upcoming trial data to inform WHO policy process.
  • Trustee, Malaria No More UK.”

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