THE BIGGEST charity donation yet by Bill Gates, the boss of Microsoft, was announced yesterday. The Bill and Melinda Gates Foundation said it will give $750m (pounds 460m) over five years to help vaccinate children in developing countries against killer diseases.

The donation to the Global Fund for Children's Vaccines is the largest ever by the foundation. The fund will work with Unicef, the World Bank, the World Health Organisation and pharmaceutical companies to buy vaccines and encourage governments to boost immunisation programmes.

"There are existing vaccines which, if distributed properly, could save three to four million children's lives a year," said James Wolfensohn, president of the World Bank.

The foundation gave $100m last year to help speed vaccines to children in poor countries, focusing on respiratory and liver diseases and diarrhoea.