Being Prepared: Modeling the Response to an Anthrax Attack

On 1 February 2005, Connecticut residents heard an emergency alert broadcast, beginning at 2:10 p.m. and ending at 3:10 p.m., that ordered them to evacuate the state. Fortunately, their response was minimal. A state emergency management official had mistakenly entered the wrong computer code into a weekly test of the emergency alert system, and incredulous Connecticut residents had correctly assumed that the broadcast was a false alarm. The incident illustrates several difficulties in preparing for a future catastrophe. Potential catastrophes differ in form, scale, and predictability, and each requires specific consideration of risk and preparation. If we could predict with certainty when and where a particular catastrophic event would occur, we could prepare with total commitment. Alas, to quote the physicist Niels Bohr: “Prediction is very difficult, especially about the future” (1).

In this issue, Fowler and colleagues (2) analyze the issues of preparedness for a specific potential catastrophe: a large-scale anthrax attack on a U.S. city. They focus on medical logistics and cost-effectiveness analyses of preattack and postattack strategies. Their method is decision-analytic modeling, which uses computer simulations to predict large-scale system outcomes based on assumptions about the probability of small-scale events. The model tracks individuals as they pass through various health states. Transition from one state to another is a matter of chance, as determined by probabilities derived from published studies. The mathematical modeling allows comparison of different strategies of preparation and response in terms of probabilities of vaccination, vaccination …