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Donors from around the world have pledged $4.3bn for a programme that aims to vaccinate 250 million of the world's poorest children against life-threatening diseases.

The pledges surpass the $3.7bn target set by the Global Alliance for Vaccines and Immunisation (GAVI), which says it could prevent more than four million premature deaths by 2015.

Britain and Bill Gates, the Microsoft chairman, have jointly committed $2.3bn to help vaccinate more than 80 million children in impoverished countries.

Speaking to Al Jazeera, Gates, a billionaire and philanthropist who helped set up the alliance, says his charitable foundation will commit an additional $1bn over five years.

Source: Al Jazeera