Washington, United States --- A new approach using existing medicines to prevent malaria has been shown to reduce severe cases of the parasitic disease among infants by more than 70 percent in sub-Saharan Africa, according to a study.

The "dramatic" results, published in the New England Journal of Medicine on Wednesday, came from combining booster shots of an antimalarial vaccine ahead of the rainy season together with preventative drugs.

Malaria kills more than 400,000 people a year, the vast majority under the age of five.

The paper's senior author Brian Greenwood of the London School of Hygiene and Tropical Medicine told AFP that members of the team were in touch with the World Health Organization about updating its recommendations.

The RTS,S vaccine, made by British pharmaceutical company GSK, was developed more than 20 years ago but by itself is not highly effective, said Greenwood.

Prior research has shown the vaccine's protection wanes over time and it offers around 30 percent efficacy over a period of three to four years.

Since malaria is highly seasonal in the Sahel and sub-Sahel region, the team wanted to test whether giving boosters before each year's rainy season, when mosquito populations peak, would improve outcomes.

The trial followed around 6,000 children aged five to 17 months from Burkina Faso and Mali over the course of three years.

The children were split into three groups: those who received only the anti-malarial drugs sulfadoxine–pyrimethamine and amodiaquine; those who received only the RTS,S vaccine; and those who received a combination.

The combination was the most effective intervention, reducing malaria cases by 63 percent, hospitalizations by 71 percent, and deaths by 73 percent compared to the drugs alone.

"That was pretty dramatic," said Greenwood -- stressing that these numbers are on top of the impact of the already effective drugs, not compared to no medicine, which would have been unethical to test.

He estimated that the combination of the booster vaccine doses and antimalarial drugs reduced hospitalizations and deaths by 90 percent compared to no intervention.

Children initially receive three doses of the vaccine to prime their systems, then a booster every year. It is based on a particle that trains the immune system against the Plasmodium falciparum parasite.

The anti-malarial drugs are given for three days a month every four months.

Greenwood said the study showed the value of developing plans in accordance with local epidemiological conditions -- in this case administering vaccines ahead of peak season, instead of during times when there was no transmission and their impact would fade.

"Like a lot of these things it's sort of common sense but nobody has actually put this into practice, to see whether it actually would work," he said.

"Hopefully this may get implemented in several countries and save lots of people's lives."