The R21/Matrix-M vaccine was designed in 2011 as a potential improvement on the RTS,S/AS01 malaria vaccine designed in the 1980s. A phase II trial in Burkina Faso, reporting in 2021, was the first to show that R21/Matrix-M could reach the WHO-specified target of 75% efficacy in African children. The most recent phase III results were published in The Lancet last week.
The trial investigators immunised over 4,800 young children in a trial in Burkina Faso, Kenya, Mali and Tanzania and found on average 78% vaccine efficacy over the first year of follow-up across all sites in the 5-17 month age group, 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. Safety data from the trial have been reassuring with no serious adverse events linked to immunisation. No other vaccine has reported over 55% efficacy in the same age group. A booster dose after a year maintained good efficacy over the following 6-12 months. The vaccine also reduced infection rates in children measured at 12 and 18 months after vaccination suggesting a potentially beneficial effect in reducing malaria transmission.
Malaria is the largest cause of death in young African children with over 600,000 deaths globally each year. Two vaccines have recently achieved and completed World Health Organization prequalification and initial deployments are starting early this year. To date, 25 million doses have been manufactured and are ready for roll-out by the Serum Institute of India in the next three to four months.
Professor Adrian Hill, Director and Lakshmi Mittal & Family Professor of Vaccinology at The Jenner Institute, and chief investigator of the R21/Matrix-M phase III 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 IIb trial. These data support 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.’
Adar Poonawalla, CEO, Serum Institute of India, said: ‘The Lancet study on R21/Matrix-M™ Phase III trials mark a significant advancement in our battle against this global threat. Our collaboration with the University of Oxford has been instrumental in developing the R21/Matrix-M™ malaria vaccine. We are dedicated to making this vaccine available, especially in Africa, where malaria poses a substantial threat to millions of lives, bringing us closer to a malaria-free world.’
Professor Alassane Dicko, Principal Investigator in Mali of the R21/Matrix-M vaccine said: ‘It has been very exciting to generate high efficacy data with the new R21/Matrix-M vaccine so quickly. I predict that this vaccine should be very impactful in preventing malaria deaths in African children.’
John C Jacobs, CEO of Novavax said: ‘Approximately 1,300 children die from malaria every day, a staggering statistic for a preventable disease. The R21/Matrix-M Phase III efficacy data published in The Lancet reinforce the potential of the R21/Matrix-M vaccine to protect children against this disease. We are proud of the role of Novavax's patented saponin-based Matrix-M adjuvant, which has been demonstrated to enhance the immune response, in the outcome of this clinical trial and are eager to see the realized impact of the vaccine when it is rolled out globally.’
The full paper is available here: www.thelancet.com/journals/lancet/article/PIIS0140-6736(23)02511-4/fulltext