Seth Berkley was a young epidemiologist working for the US State Department when he saw the graves left behind after measles swept through refugee camps in Sudan during the 1985 famine. “You'd see little shallow graves, lined up, one after the other - babies. That's what happens when measles goes through a nutritionally deficient community. It's a horrible disease and it spreads incredibly efficiently,” he says. Now, as chief executive of the Global Alliance for Vaccines and Immunization (GAVI), Berkley's specialism is vaccinology and he is in Africa again, working to introduce routine childhood immunisations which protect most people in the rich world. Here in Ghana, there have been no deaths from measles since 2003, and no cases of polio, another vaccine-preventable disease, since 2008. But Berkley's sights are set high. His interim goal with GAVI is to save another 4 million lives by 2015, and his big mission is for the global health community to get vaccines against every preventable disease to every child who needs protecting. “I wish we could have state-of-the-art hospitals in every corner of the earth...but realistically it's going to be a while before that can happen,” he said in an interview. “But we can immunise every kid on earth, and we can prevent these diseases. It's only a matter of political will, a little bit of money and some systems to do it.” GAVI, set up in 2000, uses private and government donor backing to negotiate down vaccine prices for the developing world and then bulk-buy and deliver them to countries whose populations need them most. In its first decade, GAVI says it has already financed immunization that has prevented more than 5.5 million premature deaths from common but life-threatening diseases.