UK finance minister (Chancellor of the Exchequer) Gordon Brown has announced the UK's promise to more than match the $750m donation from Microsoft chariman Bill Gates for a fund to support vaccines in developing countries over the next 10 years to bring the special vaccine fund's total resources to around $5bn. Brown believes this would enable the Global Alliance for Vaccines and Immunisation (Gavi) to tap financial markets and borrow money against its future resources. The chancellor and the international development secretary, Hilary Benn, will challenge rich countries to follow the UK's lead and commit a total of $4bn to Gavi over the next 10 years. The money could save 5m lives up to 2015 and another 5m after that date. Gavi, an alliance of official and non-governmental agencies, academics and vaccine manufacturers, has so far concentrated on delivering basic vaccines for diseases such as diphtheria, measles and polio.