Malaria vaccine becomes first to achieve 75% efficacy goal in trial of children

A vaccine candidate for malaria has become the first to meet the World Health Organization’s 75% efficacy target, after a trial in 450 children reported 77% efficacy.1

The phase II trial included infants aged five to 17 months from 24 villages in Nanoro, Burkina Faso. Participants were split into three groups—low dose, high dose, and a rabies vaccine control group—with doses administered from May to August 2019.

The results, released through Preprints with The Lancet, showed that the higher dose version of the vaccine had 77% efficacy and the lower dose had 71% efficacy over a 12 month follow-up period. No serious adverse events related to the vaccine were observed.

Malaria has been historically difficult to develop a vaccine against.2 Before this, the first and only vaccine shown to be effective against malaria was the RTS,S vaccine, which prevented four in 10 cases (39%) of malaria over a four year follow-up period and about three in 10 cases (29%) of severe malaria.3

Burkina Faso’s health minister Charlemagne Ouédraogo said, “Malaria is one of the leading causes of childhood mortality in Africa. We have been supporting trials of a range of new vaccine candidates in Burkina Faso and these new data show that licensure of a useful new malaria vaccine could well happen in the coming years. That would be an important new tool for controlling malaria and saving lives.”

In the trial, three vaccinations were administered at four week intervals before the malaria season and a fourth dose was given one year later. The preprint reported that at six months 43 out of 146 children (29.5%) in the low dose group and 38 out of 146 (26%) in the high dose group had developed clinical malaria. In the rabies group 105 out of 147 (71.4%) developed clinical malaria.

At 12 months (before the fourth dose), a total of 50 in the low dose, 39 in the high dose, and 106 in the control group had developed malaria. This equated to 71% efficacy for low dose and 77% for the high dose. The trial team will continue to follow up with participants for a second malaria season.

The research was funded by the European and Developing Countries Clinical Trials Partnership, the Wellcome Trust, and the NIHR Oxford Biomedical Research Centre.

The researchers, in collaboration with Serum Institute of India and Novavax, have now started recruitment for a phase III licensure trial. Around 4800 children (aged five to 36 months) are set to be recruited from four African countries.

Principal investigator of the trial and professor of parasitology Halidou Tinto said, “These are very exciting results showing unprecedented efficacy levels from a vaccine that has been well tolerated in our trial programme. We look forward to the upcoming phase III trial to demonstrate large scale safety and efficacy data for a vaccine that is greatly needed in this region.”

Co-author of the paper Adrian Hill, Jenner Institute director and professor of vaccinology at the University of Oxford, added, “With the commitment by our commercial partner, the Serum Institute of India, to manufacture at least 200m doses annually in the coming years, the vaccine has the potential to have major public health impact if licensure is achieved.”