The UK has pledged £814m to help vaccinate children in developing countries against preventable diseases.
The announcement was made at a conference in London by Prime Minister David Cameron, the host of the event, where countries were sked to provide £2.3bn by 2015 for child vaccines.
Microsoft magnate Bill Gates also said at the conference that he will offer $1bn to help the campaign.
A record 50 countries have applied for vaccine funding from the Global Alliance on Vaccines and Immunisation (GAVI) this year, compared to previous record of 27 applications in 2007.
GAVI has rolled out a range of vaccines to children in 19 countries but says it has not got the £2.3bn needed to vaccinate those in 26 others, which could save four million lives in four years.
The UK’s promise for more funding follows last week’s announcement that major pharmaceutical companies would make cuts to the prices of their vaccines in the developing world.
GlaxoSmithKline has committed to supply 125 million doses of its Rotarix vaccine to GAVI over the next 5 years at a 95% reduction of the Western market price.
Last month Germany said it will contribute €30 million to the GAVI Alliance in 2012, up from €20 million in 2011, to support childhood immunisation in developing countries.