Public health emergencies underscore the immediate and crucial need to plan for a mass disaster in which tens or even hundreds of thousands of individuals suddenly require medical care. On October 24, 2009, President Obama declared a public health emergency in response to influenza A(H1N1),1 but natural disasters (eg, hurricanes, floods, or earthquakes) and terrorism acts (eg, anthrax or a nuclear detonation) similarly demonstrate the critical need for national preparedness