So far, the project has run about 200 simulations of an avian flu epidemic, models that have helped Longini's group reach provocative conclusions that fall along two lines: how a nationwide outbreak might take hold, and what policies would best combat it.
EpiCast reveals that, in contrast with flu epidemics of decades past, an outbreak today won't progress "like a wave across the country," spreading from town to town and state to state. Instead, no matter where it erupts - Seattle, Chicago, Miami - it will swiftly blanket the nation. "It starts in Chicago one day," Germann says, "and a couple of weeks later it's everywhere at once." Thank the airlines. Even though disease has piggybacked on air travel for decades, we generally had only isolated outbreaks of low-transmission viruses - like when SARS leapt from Hong Kong to Canada in 2003 but failed to spread beyond Toronto. In an epidemic of a highly communicable disease, the airlines' hub network would effectively seed every metropolitan area in the country within a month or two - and then reseed them, repeatedly.
EpiCast showed that local intervention measures can have some impact: Close the schools, enforce a quarantine, and the disease will slow down. That buys the federal government time to develop and mass-produce a vaccine. But Germann quickly adds a caveat: Acting locally may not be enough. In a worst-case outbreak, without a viable vaccine, "the disease will climb, and eventually go exponential. And once it's on the exponential curve, it's very difficult to contain.
EpiCast reveals that, in contrast with flu epidemics of decades past, an outbreak today won't progress "like a wave across the country," spreading from town to town and state to state. Instead, no matter where it erupts - Seattle, Chicago, Miami - it will swiftly blanket the nation. "It starts in Chicago one day," Germann says, "and a couple of weeks later it's everywhere at once." Thank the airlines. Even though disease has piggybacked on air travel for decades, we generally had only isolated outbreaks of low-transmission viruses - like when SARS leapt from Hong Kong to Canada in 2003 but failed to spread beyond Toronto. In an epidemic of a highly communicable disease, the airlines' hub network would effectively seed every metropolitan area in the country within a month or two - and then reseed them, repeatedly.
EpiCast showed that local intervention measures can have some impact: Close the schools, enforce a quarantine, and the disease will slow down. That buys the federal government time to develop and mass-produce a vaccine. But Germann quickly adds a caveat: Acting locally may not be enough. In a worst-case outbreak, without a viable vaccine, "the disease will climb, and eventually go exponential. And once it's on the exponential curve, it's very difficult to contain.
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