New Malaria Vaccine Shows Most Efficacy of Any to Date: Small Trial
Immunization had up to 77 percent efficacy in a Phase 2 clinical study of 450 children in Burkina Faso.
Amalaria vaccine developed by researchers at the University of Oxford’s Jenner Institute had up to 77 percent efficacy in a small clinical trial among children in Burkina Faso. The findings, posted as a preprint last week (April 20), represent the highest efficacy of any vaccine for the disease, although some researchers have cautioned that more data are needed before drawing firm conclusions about just how well it works.
The study results are “very positive news,” Pedro Alonso, the director of the World Health Organization (WHO) Global Malaria Programme, who was not involved in the work, tells Science. The trial only included 450 children, he adds. “We are still quite far away from having the type of information that would allow us to get very excited.”
Malaria kills more than 400,000 people each year. Most of those deaths are in Africa, and most are among young children. Previous attempts to develop a vaccine have been hindered by the complexity of the malaria parasite—any of several species in the genus Plasmodium—which invades host cells and whose genome contains thousands of genes.
It’s a “real technical challenge,” study coauthor Adrian Hill, a vaccinologist and director of the Jenner Institute, tells BBC News. “The vast majority of vaccines haven’t worked because it’s very difficult.”
The WHO has previously set a target of 75 percent efficacy for a malaria vaccine. Efficacy is measured as the reduction in disease incidence in vaccinated people compared to unvaccinated ones in a trial.
Before the current study results were posted, the most efficacious vaccine was GlaxoSmithKline’s Mosquirix, which showed around 56 percent efficacy in Phase 3 trials with young children after a year of immunization and is currently being deployed in several sub-Saharan countries. Follow-ups with immunized children showed that the vaccine prevented around 39 percent of malaria cases and 29 percent of severe cases in the four years following immunization.
Datoo et al.2021: High Efficacy of a Low Dose Candidate Malaria Vaccine, R21 in 1 Adjuvant Matrix-M™, with Seasonal Administration to Children in Burkina Faso. The Lancet (in press). DOI: 10.2139/ssrn.3830681