International donors have pledged more than $4 billion to vaccinate children against life-threatening diseases such as pneumonia and measles.

At a one-day conference in London Monday, Britain led the donations with a contribution of $1.3 billion.

The Bill and Melinda Gates Foundation declared it would donate more than $1 billion to the cause over the next five years.

The money was donated to the Global Alliance for Vaccines and Immunization, which says the funding will help vaccinate more than 250 million children, saving 4 million lives.

Among other donors, Norway gave more than $670 million, the United States pledged $450 million and Australia contributed more than $200 million.

Liberian President Ellen Johnson Sirleaf hailed the conference as an important moment in the commitment to protect children. However, she warned against complacency, saying that every 20 seconds a child still dies of a vaccine-preventable disease.