There have been 3 flu pandemics since 1918: 1957, 1968, 2009. In addition, cholera and AIDS have had non-influenza pandemics in the same timeframe, and there's a clutch of infectious diseases with little spread that qualify as pandemics by the definition of sustained spread in two countries in different regions of the world (e.g., mumps). MERS might also qualify by the definition.