Air-travel restrictions won't halt spread of bird flu, finds computer simulation

SAN FRANCISCO — Closing international airports will do little to halt a bird flu outbreak, British health officials reporteed in a medical journal, the third such computer simulation that shows the folly of travel restrictions in the face of a pandemic.

"Even if 99 percent of international air were stopped, every country would in all probability still be infected Ben Cooper,of England's Health Protection Agency, said Monday. He also is an author of the study being published in the online science journal PLoS Medicine. "Even if 99.9 percent of travel were stopped, very few cities would escape the pandemic."

The computer-predicted scenario by the agency was published a week after researchers at Imperial College in London showed the United States could do little to slow a pandemic if it hit now.

Cooper said the computer model was based on "optimistic assumptions" and that shutting down nearly all air travel won't stop the flu's spread because there isn't enough vaccine to inoculate everybody.

A third study in the Proceedings of the National Academy of Sciences earlier this month suggested that even a 90 percent reduction in domestic travel would slow the spread of the flu in the United States by only a few days to weeks and would not reduce the eventual size of the outbreak.

"Once pandemic strains are widespread, it doesn't make any sense to impose travel restrictions," said Ira Longini, a University of Washington researcher who co-wrote the PNAS paper. "You simply can't contain the flu with travel restrictions."

A draft of a national response plan to bird flu could lead the Bush administration to limit international flights, quarantine exposed travelers and otherwise restrict movement in and around the country, according to a draft obtained Monday by The Associated Press.

But a complete shutdown of the border would not be likely, nor would it do more than slow the pandemic's spread by a few weeks, according to the plan expected to be released as early as Wednesday.

So far this year, H5N1 bird flu — which is not yet pandemic flu because it doesn't move easily between people — has infected 204 people and killed 113, according to the World Health Organization. Most of the human cases and deaths have been in Asia, but birds with the disease have been found in Europe.

The scientists behind the bird flu models said influenza spreads from person to person much faster than SARS and other diseases. Also, some people infected with the flu show no signs of sickness, but can still pass the illness on.