Rate of the spread of flu Is linked to airline travel

The New York Times today reports on a PLoS Medicine study by Brownstein, Wolfe & Mandl showing that the rate of spread of influenza is related to the number of people flying in airplanes.

They studied the spread of influenza timed to the amount of air travel from 1996 to 2005. From year to year, the day that marks the highest number of deaths (peak mortality) due to flu is Feb. 17. But following Sept. 11 and the subsequent decrease in air travel, the peak mortality was delayed until March 2.

Considering that during the SARS outbreak, transmission occurred between travelers on the same airplane from Hong Kong to Singapore, it's plausible that air travel poses some risk to contracting not only flu but other infectious airborne illnesses.

The authors argue that in the case of pandemic flu, the government should use restrictions on air travel to decrease the rate of spread:

"Restricting travel would provide critical lead time to stockpile antivirals, develop vaccines, decide on school closures and lessen person-to-person contact," said Dr. Kenneth D. Mandl, the study's senior author.

"Flight restrictions might give us a chance to reduce downstream illness and deaths in a flu pandemic," said Dr. Mandl, an assistant professor of pediatrics at Harvard and an attending physician at Children's Hospital Boston. "If we can provide a month of lead time, that gives us an advantage."

Dr. John S. Brownstein, the paper's lead author and an instructor in pediatrics at Harvard, added that restricting air travel as a pandemic control measure would have major economic and social impact.

"It is for policy makers to decide, and we hope to have provided them with the evidence they need to gauge the possible benefit of that decision," Dr. Brownstein said. "Clearly an air traffic ban would be one of multiple measures that could help mitigate the impact of a flu pandemic."

Hundreds of articles commenting on this at Google News.

References:
Brownstein JS, Wolfe CJ, Mandl KD (2006) Empirical evidence for the effect of airline travel on inter-regional influenza spread in the United States. PLoS Med 3(10): e401.

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