Every year, more than one million children under the age of five die as a result of diarrhoea. It is the second-biggest killer in this age group, after pneumonia, and 40% of diarrhoea deaths are caused by rotavirus. That horrific toll could soon fall, thanks to the first major roll-out of rotavirus vaccines in Africa, where half of rotavirus deaths occur. The programme was unveiled this week by the GAVI Alliance — formerly the Global Alliance for Vaccines and Immunisation — based in Geneva, Switzerland.