As of late March, no country or agency had formally declared its intent to employ the containment strategy in Asia, but the World Health Organization has a stockpile of Tamiflu in the region. If models show that intervention has a good chance of success, says WHO spokesman Dick Thompson, the agency will convene experts to talk about implementing a concrete plan.

Longini, who expected to have his full results published in April, thinks that in the real event, an emerging H5N1 virus can be contained with antivirals, provided its R0 is less than 1.4 and the intervention begins within two or three weeks of the outbreak's start. He is already at work on new models to determine how the avian virus is likely to evolve as it gets better at spreading between people. "I really strongly believe that the R0 will start out low, probably a little above 1," Longini says, "and then with each generation of transmission it will increase as [the virus] adapts to the human population. It gives us a strong window of opportunity to intervene before the R0 evolves to a high enough level where it's basically unstoppable."

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