London (CNN) -- Over $4.3 billion was pledged by major public and private donors at a conference in London on Monday to aid projects vaccinating children in developing countries.
The conference -- co-hosted by the British Government and the Global Alliance for Vaccines and Immunization (Gavi) -- had hoped to raise $3.7 billion.
Donors included corporations, philanthropists like Microsoft co-founder Bill Gates and governments donating to Gavi for the first time, including Japan and Brazil.
"Today is an important moment in our collective commitment to protecting children in developing countries from disease," said President of Liberia Ellen Johnson Sirleaf in a written statement.
British International Development Secretary Andrew Mitchell, said: "We have exceeded the figure that we set ourselves and we have received firm pledges for a sum of $4.3 billion."
The pledges bring Gavi's total available resources for the period 2011 to 2015 to $7.6 billion. Gavi is aiming to immunize 243 million more children by 2015.
The British government will donate an additional $1.32 billion (£814 million) the British Prime Minister David Cameron announced Monday in a speech.
Cameron said: "In addition to our existing support for Gavi, we will provide £814 million of new funding up to 2015. This will help vaccinate over 80 million children and save 1.4 million lives."
The British Department for International Development says vaccines save the lives of 7,000 children every day.
Bill Gates, the billionaire philanthropist, told the conference that his Bill and Melinda Gates Foundation was pledging an additional $1 billion over the next five years to help the vaccination campaign.
Gates said: "It's not every day you give away a billion dollars but for a cause like this it's exciting to be doing this."
The government of Norway pledged an additional $677 million, Australia $149 million, Brazil $12 million and Japan $9 million.
According to Gavi -- a Geneva-based organization set up to increase access to immunization in the world's poorest countries -- one child dies every 20 seconds from a "vaccine-preventable disease."
Two million under-fives die from pneumonia each year despite the existence of a vaccine to protect them, says Gavi.
A recent study by the charity Save the Children reported that there are about 24 million children in the world, mostly in developing countries, who have no access to vaccines.