UPDATE 1-Gates, UK take lead in $7.5 bln pledge for children's vaccines

* Vaccine alliance hopes to immunise 300 million children

* Gates donates $1.55 bln, wants to halve child deaths

* GAVI buys vaccines in bulk for poor countries (Adds details, quotes and reactions)

By Stephen Brown

BERLIN, Jan 27 (Reuters) - International donors pledged $7.5billion on Tuesday to immunise 300 million children in poorcountries against deadly diseases such as diarrhoea andpneumonia.

At a Global Alliance for Vaccines and Immunisation (GAVI)conference in Berlin, Microsoft founder Bill Gates and theBritish government topped the donations list at $1.55 billionand $1.5 billion respectively.

German development minister Gerd Mueller said the totalreached $7.54 billion, surpassing GAVI's target of $7.5 billion,despite a stronger dollar complicating funding efforts.

Other major donors included the United States, Norway andGermany. China, a recipient of GAVI assistance early lastdecade, has now become a donor.

"It was a bold ask to world leaders but also a verycompelling case," said GAVI chairman Dagfinn Hoybraten. "In thecourse of five years from 2016 to 2020 we could vaccinateanother 300 million children and avert 5-6 million futuredeaths."

Gates, who has donated $4 billion to GAVI since it began 15years ago, said there had been "amazing" progress but one in 20children still died before their fifth birthday.

"The goal for the next 15 years is to cut that in half againto get it to one in 40," he said.

GAVI has provided vaccines to about 500 million childrenworldwide and saved 6-7 million lives from diseases likepneumonia, hepatitis B, diarrhoea and measles, working with theWorld Health Organisation, UNICEF, World Bank and charities.

Michael Elliott of anti-poverty group One, calling GAVI away for rich countries to give "an infinitesimal part of theirtax money to save lives".

But Save the Children's Jasmine Whitbread said the problemswere still huge: "In some of the world's poorest communitiesonly 16 percent of children are reached by vaccines."

GAVI funds immunisation for countries that cannot affordthem, using its buying power to negotiate discounts from thelikes of GlaxoSmithKline and Pfizer. Medicalcharity Medecins Sans Frontieres argues that it should strikeeven tougher deals.

Pfizer has said it would cut pneumococcal vaccine prices by6 percent for poor countries through 2025, including those thatoutgrow their eligibility for GAVI. GlaxoSmithKline has extendedits price-freeze commitment to 10 years for countries graduatingfrom GAVI and Sanofi will expand production of yellowfever vaccine.

But GAVI's CEO Seth Berkley called the latest discount for pneumococcal vaccine "small" and said he hoped new manufacturerswould emerge to help bring about bigger price reductions. (Editing by Ben Hirschler and Robin Pomeroy)