Progress may have been made towards a vaccine against one of the biggest killer diseases in the world.

A vaccine for malaria developed in a joint project between the UK and Gambia, so far has only a moderate success rate.

However, its inventors are hopeful the principle can be refined to make it much more effective.

Traditionally, efforts to protect against malaria have met with very little success.

An estimated 2.7m die every year as a result of the disease, which is carried by certain types of mosquito, and common across large swathes of the globe.

The majority of these deaths are among children.

Some protection

It is caused by a parasite which can invade the patient's cells, and which multiplies within the body.

The vaccine aims to prevent the parasite, Plasmodium falciparum, from invading red blood cells, which will prevent it from reaching the part of the body where it reproduces.

A year-long trial of 306 male, adult volunteers found the vaccine, if four doses are given, achieves a 47% effectiveness.

A single dose protected 34% of the the group.

Children next

It will now proceed to bigger trials - the scientists involved are hopeful that it will prove more effective when used on children.

Dr Kalifa Bojang, of the Medical Research Council Laboratories in Banjul, Gambia, said the results were encouraging, showing scientists were on the right track.

"The important thing to bear in mind that this 34% was in adults and the immune response in children might be different," he said.

Trials will now be expanded into Mozambique - and will be tested on children aged between one and five.

The study can be found in The Lancet medical journal.