The sharp drop in air travel after the attacks on New York and Washington in 2001 holds a lesson that could help thwart a future flu pandemic or even a bioterror attack.
Some 1.7 million fewer international passengers travelled to and from the US during September 2001- a drop of 27 per cent. This may have slowed flu transmission, delaying the onset of the 2001-2002 US flu season by two weeks.
The findings, which relate to ordinary flu, differ from computer models that suggested it would take a 99 per cent reduction in air travel to achieve this length of delay for pandemic bird flu. 鈥淥ur study suggests that you could get more benefit than the simulations show,鈥� says John Brownstein of the Children鈥檚 Hospital Boston, Massachusetts, who led the study. He thinks a 50 per cent reduction in air travel could create a delay of about one month.
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Brownstein鈥檚 team analysed government records of flu and pneumonia deaths between 1996 and 2005. In five of the winters, flu deaths peaked in the US within two days of 17 February. But in 2002 the peak occurred on 2 March 鈥� 13 days later than usual. In France, where no flight restrictions were imposed, there was no delay in flu deaths.
Epidemiologists say that imposing restrictions on airline travel could buy critical time during a flu pandemic or an outbreak of smallpox unleashed by terrorists. This could enable public health coordinators to stockpile vaccine.
