While speaking to people during a public phone-in event organized by Save the Children, Bill Gates, the founder and former CEO of Microsoft, called for more funding in order to help vaccinate and save the lives of the world’s poorest children.

The phone-in conversation took place in advance of a summit meeting of the Global Alliance for Vaccines and Immunizations, a vaccine-buying alliance representing governments, the pharmaceutical industry, and organizations such as Unicef. The organization is aiming to raise an extra £2.3 billion to save four million lives over the next five years.

Mr. Gates, who will be attending the summit, has already pledged $10bn (£6.3 bn) of his personal fortune to support research into new vaccines as well as funding ways to actually get the vaccines to children in need.

Vaccinations are believed to be one of the best and most cost-effective ways of protecting children. However, there are a number of challenges of administering the vaccines in some countries as a result of cultural opposition. In some countries, vaccines are not believed to provide any great benefits and there is also a lot of fear and stigma surrounding their use.

Mr. Gates is optimistic that vaccines may soon be created that can protect against polio and malaria within three years.

"Then we will have to raise more money to make sure every kid gets it”, he said.