"Recent pandemics illustrate another problem that must be faced with an impending pandemic. The time between recognition of the emergence of a new pandemic virus and the occurrence of the first wave may be short. The lead time for the production and distribution of the currently licensed influenza vaccine, trivalent influenza vaccine is 6 months. It is highly unlikely that sufficient vaccine can be produced, distributed and administered to the entire population before the first wave of the pandemic. In 1918 and 1957, the first wave of the pandemic peaked in late October allowing less time than usually occurs before the onset of interpandemic outbreaks, in the usual sequence of vaccine production starting in January."