Los Alamos National Laboratory supercomputer models indicate that targeted vaccinations and early detection may provide the best way to contain the spread of a deadly virus.

Imagine that one day soon, a dozen travelers infected with highly contagious bird flu land in Los Angeles, California. Public health officials have fretted about this threat for years. If transmission of the deadly virus isn’t stopped, thousands, hundreds of thousands or—in an absolute worst-case pandemic—millions of Americans could die. What should authorities do?

The answer, strangely enough, arrives via supercomputer programs that study the strength of metals and other materials. Developed at Los Alamos National Laboratory (LANL), in Los Alamos, New Mexico, those programs model how billions of individual atoms jostle and collide. This atomic behavior is similar to how people move and interact when they commute to work, head to school or go shopping, said Tim Germann, a LANL computer scientist. To study the issue, Germann and his colleagues teamed with influenza researchers to develop the world’s most sophisticated predictions of how bird flu would spread, and how to cope with it.

During their work, they found that a multipronged strategy would best contain the virus. “Individual strategies don’t work well by themselves,” said Germann. No one before had looked carefully at what might happen when deploying multiple strategies. Their models showed that restricting travel and a combination of vaccination and distribution of antiviral medications would work synergistically to minimize deaths.

“It’s much more efficient to have two or three mitigation strategies that alone aren’t 100 percent perfect,” said Kai Kadau, another LANL computer scientist on the project. For instance, “social distancing strategies,” such as closing schools, grounding commercial air travel or encouraging telecommuting, would help slow the spread of bird flu. Such measures alone, however, would not halt the disease. But by distributing antiviral medications in communities hit by the flu and vaccinating people widely, the virus would eventually stop spreading. “Restricting travel slows it down significantly and buys you some time to put some other strategies in place, such as developing a better vaccine,” Kadau added.

The models also show that distributing even a weak vaccine can help stanch the virus, although this finding surprised a lot of infectious disease experts. “On an individual level, the vaccine isn’t very effective,” Germann said. “If a large enough portion of the population is vaccinated, the collective benefit is pretty big.” Policymakers took note of the findings. Now vaccine developers are stockpiling a vaccine targeted to the strain of bird flu circulating mainly among poultry in Asia.

Slowing the spread of the virus among school children should also be a top priority, said Germann. Reducing transmission by closing schools or vaccinating children would play a major role in halting a burgeoning pandemic. Children’s immune systems are weaker than those of adults, as evidenced by the high proportion of school kids that contract the flu strain that circulates each winter. “If you can slow or stop the spread among school children, that’s your biggest benefit,” said Germann.

Previous attempts to model bird flu relied on crude estimates of the virus spreading from community to community. But by mining U.S. census data, the new models predict the day-to-day movements of all 300 million Americans. Such a detailed approach had never been tried before, but the supercomputers at LANL have more than enough “horsepower” to get the job done. In fact, if good census data existed for the entire world, the computer models Germann and colleagues built could even estimate how bird flu would spread across the globe. “There’s no technical reason why we couldn’t study the worldwide emergence of the human virus from Southeast Asia,” Germann said. “But we’re data-limited there. The United States has excellent census data on how people commute and travel, something you don’t find in the rest of the world.”

LANL researchers also have built a database of all known strains of influenza and, in another project, modeled how the flu and other viruses, such as hepatitis C, mutate and evolve. Such work is crucial for developing new antiviral medications, said Harel Dahari, a theoretical biophysicist at LANL. Together, the projects provide policymakers with hard data crucial for stopping bird flu from exploding into the deadliest pandemic of all time—a real fear among public health experts. The U.S. National Laboratories reviewed the bird flu computer models and “went in skeptical but came out saying these models are really useful,” said Germann.

Subsequently, the U.S. Centers for Disease Control and Prevention (CDC) released policies on bird flu mitigation that incorporate key findings from the model. LANL researchers also are working with the U.S. Department of Homeland Security (DHS) to develop simplified computer models cities can use to build their own local plans.