Plasmodium falciparum

WHO/TDR/Taylor-Robinson

A malaria vaccine has performed well in a small clinical trial of adults in Mali, leading to testing being expanded to children.

The results of the adult trial — carried out by Mahamadou Thera and colleagues from the Malaria Research and Training Center of the University of Bamako in Mali, and US universities — were published this month (23 January) in PLoS One.

Sixty Malian volunteers between the ages of 18 and 55 from Bandiagara — a rural town in northeast Mali where malaria is common — were injected with either a full or half dose of the malaria vaccine or a control rabies vaccine, to distinguish between natural, background immunity and that which is induced by the vaccine.

The participants were injected three times over three months, beginning at the end of the malaria transmission season. At the end of the following malaria season, participants receiving the vaccine had up to six times the amount of antibodies to Plasmodium falciparum — the malaria parasite — as they has at the beginning of the study.

The vaccine, 'FMP2.1/AS02A', is based on a protein of P. falciparum and two immuno-stimulants, including a compound from the soap bark tree, long used in traditional medicines in Latin America.

Researchers are now conducting phase I and II clinical trials in the same region, this time among 400 children aged between one and six in the Dogon country outside Bandiagara.

Children younger than ten suffer on average two clinical malaria episodes every rainy season, while severe malaria afflicts 1 in 50 children under six years old in the region every year.

Sheick Oumar Coulibaly — a malaria researcher at the University of Ouagadougou in Burkina Faso — praises the research, but warns that it will be a long time before a vaccine finishes all safety and effectiveness tests, gains regulatory approval and production is scaled up to become commercially available.

"The discovery of an efficient vaccine against malaria will certainly not be made at once, since the parasite is very complex,'' he said. ''But with the results of this trial, a new path has been found towards the discovery of an efficient anti-malaria vaccine."

Link to full paper in PLoS ONE

Reference: PLoS ONE 3, e1465. doi:10.1371/journal.pone.0001465 (2008)