Pandemic influenza poses a threat to public health at a time when the United Nations' World Health Organization (WHO) has said that infectious diseases are spreading faster than at any time in history. The last major influenza pandemic occurred from 1918 to 1919. Estimates of deaths worldwide if a similar pandemic were to occur have ranged between 30 million and 384 million people. Individual countries and international organisations have developed and begun to implement a strategy for forestalling (that is, containing, delaying, or minimising the impact of) the onset of a pandemic. Antivirals and vaccines may help forestall a pandemic. This is an excerpted and indexed version.