A major trial of the world's first malaria vaccine is under way in Africa - starting with Malawi, followed by Kenya and Ghana.

The disease which is spread by mosquitos kills more than 400,000 people every year, most of them young children.

Almost $1bn has gone into developing the vaccine over three decades.

Initial testing of RTS the world's first anti-malaria vaccine has indicated it reduces cases by about 40%.

Video producer: Rupert Waring for Focus on Africa TV.