Bill and Melinda Gates in Davos, Switzerland, January 29, 2010. FABRICE COFFRINI/AFP/Getty Images hide caption

itoggle caption FABRICE COFFRINI/AFP/Getty Images

A syringe and vials of swine flu vaccine at a hospital in Essen, Germany, last year. Martin Meissner/AP hide caption

itoggle caption Martin Meissner/AP