Real modeling, from rocket scientist guys:
Simulation of a pandemic flu outbreak in the continental United States, initially introduced by the arrival of 10 infected individuals in Los Angeles…. Without vaccination, antiviral drugs, or other mitigation strategies, the entire nation becomes infected within a few months. Depending on the reproductive number R0, effective intervention strategies including vaccination and targeted antiviral prophylaxis can be successful without resorting to economically damaging measures like school closure, quarantine, and work or travel restrictions. This large-scale agent-based simulation involves 280 million people, and uses demographic and worker flow data at the Census tract level, as well as long-range travel statistics, to describe the geographic movement of people.
There’s a quicktime movie that visualizes the spread.