According to the World Health Organisation’s estimates, three million children under five die in Africa every year, from diseases that could be prevented by vaccines. The Global Alliance for Vaccines and Immunisation, GAVI, plans to immunise up to three hundred million more children all over the world by 2020. CNBC Africa caught up with Ngozi Okonjo Iweala, Chair of GAVI and discussed how the organisation plans to accomplish its ambitious goal.