Bite-mimicking malaria vaccine shows promise, says studies

PARIS: A malaria vaccine that mimics a mosquito bite yielded encouraging results in human trials, its makers said yesterday, raising hopes for thwarting a parasite that kills a child every two minutes.

The candidate drug, called PfSPZ, provided up to 100 per cent protection for 10 weeks in a trial in Germany, although a trial in real life conditions in Mali gave a lower level of defence, they reported in two separate studies.

“We are extremely encouraged by these findings,” said Stephen Hoffman of vaccine developer Sanaria, a company based in Maryland.

But he stressed a lot of work lay ahead, and a registered vaccine may take another two years to reach the market.

PfSPZ uses a live, immature form of the malaria parasite, called a sporozoite, to stimulate an immune reaction in humans.

In one trial, a version of PfSPZ required fewer shots and a lower dose of live malaria parasites than tested to date, researchers reported in the science journal Nature.

For another form of the vaccine, sporozoites are exposed to radiation to weaken them before being injected into the human bloodstream.

A previous trial with the irradiated version saw 44 trial volunteers given five shots, each with up to 135,000 sporozoites, or three doses with up to 1.8 million sporozoites in total.

The highest dose conferred up to 100 percent immunity, a 2013 report said.

For the German trial, volunteers were given only three injections over eight weeks or 10 days, with sporozoite doses ranging from 3,200 to 51,200 per shot.

All nine volunteers in the high- dose group enjoyed malaria protection 10 weeks after the last dose, compared to six out of nine in the medium- and three out of nine in the low- dose groups, said Hoffman.