London: A malaria vaccine booster shot at one year following a primary three-dose regime maintained high efficacy of 70-80 percent against the disease, according to a study published in The Lancet Infectious Diseases journal. Researchers from the University of Oxford, UK, and colleagues reported the findings from their Phase 2b trial following the administration of a booster dose of the candidate malaria vaccine, R21/Matrix-M.
The vaccine, licensed to the Serum Institute of India, previously demonstrated high-level efficacy of 77 percent over the following 12 months in young west African children in 2021.
In their latest findings, the researchers found that a vaccine booster dose at one year following a primary three-dose regime continued to meet the World Health Organization’s Malaria Vaccine Technology Roadmap goal of a vaccine with at least 75 percent efficacy.
A total of 450 participants aged five to 17 months were recruited from Burkina Faso, with 409 receiving the booster.
The participants were randomly assigned to three groups, with the first two groups receiving the R21/Matrix-M 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 study reports a vaccine efficacy of 80 percent in the higher-dose adjuvant group, and 70 percent 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, the researchers said. No serious adverse events related to the vaccine were noted, they said.
”It is fantastic to see such high efficacy again after a single booster dose of vaccine. We are currently part of a very large phase III trial aimed at licensing this vaccine for widespread use next year,” said Halidou Tinto, the trial Principal Investigator.
”We are delighted to find that a standard four-dose immunisation regime can now, for the first time, reach the high efficacy level over two years that has been an aspirational target for malaria vaccines for so many years,” said Professor Adrian Hill, from the University of Oxford.
The trial has been extended for another two years to assess if further booster doses will be necessary to maintain high efficacy over time.
Results from the key ongoing Phase III licensure trial to assess large-scale safety and efficacy in 4,800 children aged five to 36 months across four African countries are also expected later this year.