Snowy Owl
Retired in 2010, In Memoriam
<!-- story starts here--> <table border="0" cellpadding="0" cellspacing="0" width="411"> <tbody><tr> <td valign="top" width="271">[SIZE=+2]Grounding air travel won't substantially slow spread of pandemic flu: study
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http://travel.canoe.ca/Travel/News/2006/05/01/1559648-cp.html
By Helen Branswell
[/SIZE]TORONTO (CP) - World leaders could face serious pressure to impose travel bans on affected nations in the early days of a flu pandemic. But even grounding virtually all air travel would only serve to moderately delay spread of a pandemic strain, a new study suggests.
Using mathematical models, researchers with Britain's Health Protection Agency concluded that even if 99.9 per cent of air travel could be halted, a pandemic strain would be delayed from hitting most cities by, at most, about four months.
"Even large and widely enforced travel restrictions would usually delay epidemic peaks by only a few days," the authors wrote in the journal Public Library of Science Medicine. "To have a major impact, restrictions would have to be almost total and almost instantaneous."
A leading U.S. modelling expert said the findings confirm work he and other groups have shown - that flu cannot be contained this way.
"It spreads so fast and the epidemics are so explosive that (in spite of) almost anything you do, cases are going to get through unless you're incredibly - unrealistically - effective at . . . shutting down transportation," said Ira Longini of the School of Public Health and Community Medicine at the University of Washington.
"It's just not a practical control strategy. It just buys you a few weeks at best." And that's not enough time to make a real difference. It wouldn't be sufficient time, for instance, for the few countries with flu vaccine production capacity to protect their citizenry by making and widely administering a vaccine.
"Even when 99.9 per cent of air traffic was suspended, most cities had a low probability of ultimately escaping the pandemic and delays large enough to be of clinical significance (six months or more) were common only if interventions were made after the first few cases," wrote the authors, who are with the British agency's Centre for Infections.
The study was not commenting on the likelihood of success of the World Health Organization's plan to try to contain a pandemic at source.
That plan, supported by mathematical models, hypothesizes that it might be possible to extinguish an nascent pandemic strain in the very early days if movement out of the area where it emerged was cut off and if people within the area were given antiviral drugs to prevent spread of flu.
In fact, the authors of this study suggest focusing resources on that containment effort would probably be more valuable than drawing up plans to ban air travel once a pandemic has started.
Grounding all international air travel would create huge problems for the transport of essential goods and would decimate an already fragile industry.
The director of immunization and respiratory infections for the Public Health Agency of Canada said this study, along with two other recent modelling efforts, reinforces the belief of experts that grounding planes isn't an appropriate response.
"Shutting down plane travel is unlikely to be effective or sustainable because of the way influenza behaves," said Dr. Theresa Tam. Some diseases lend themselves to containment using travel restrictions - something like SARS, for instance, where only people showing symptoms were infectious and there was a long incubation period that allowed authorities to monitor people who'd been exposed.
But influenza is not one of them. Flu has a short incubation period, typically one to four days. And people who are incubating the disease can spread it before realizing they are sick.
The authors conclude that attempting to screen incoming air travellers for disease once a pandemic has started would also be a wasted effort, saying "such an intervention would have a negligible impact on the course of a pandemic once it was underway."
They suggested that rather than working on strategies to restrict travel in the early phases of a pandemic, public health authorities should focus their efforts on planning ways to slow spread within a community once a pandemic strain has arrived. School closures are considered one possible way to slow spread.
</td></tr></tbody></table>
http://travel.canoe.ca/Travel/News/2006/05/01/1559648-cp.html
By Helen Branswell
[/SIZE]TORONTO (CP) - World leaders could face serious pressure to impose travel bans on affected nations in the early days of a flu pandemic. But even grounding virtually all air travel would only serve to moderately delay spread of a pandemic strain, a new study suggests.
Using mathematical models, researchers with Britain's Health Protection Agency concluded that even if 99.9 per cent of air travel could be halted, a pandemic strain would be delayed from hitting most cities by, at most, about four months.
"Even large and widely enforced travel restrictions would usually delay epidemic peaks by only a few days," the authors wrote in the journal Public Library of Science Medicine. "To have a major impact, restrictions would have to be almost total and almost instantaneous."
A leading U.S. modelling expert said the findings confirm work he and other groups have shown - that flu cannot be contained this way.
"It spreads so fast and the epidemics are so explosive that (in spite of) almost anything you do, cases are going to get through unless you're incredibly - unrealistically - effective at . . . shutting down transportation," said Ira Longini of the School of Public Health and Community Medicine at the University of Washington.
"It's just not a practical control strategy. It just buys you a few weeks at best." And that's not enough time to make a real difference. It wouldn't be sufficient time, for instance, for the few countries with flu vaccine production capacity to protect their citizenry by making and widely administering a vaccine.
"Even when 99.9 per cent of air traffic was suspended, most cities had a low probability of ultimately escaping the pandemic and delays large enough to be of clinical significance (six months or more) were common only if interventions were made after the first few cases," wrote the authors, who are with the British agency's Centre for Infections.
The study was not commenting on the likelihood of success of the World Health Organization's plan to try to contain a pandemic at source.
That plan, supported by mathematical models, hypothesizes that it might be possible to extinguish an nascent pandemic strain in the very early days if movement out of the area where it emerged was cut off and if people within the area were given antiviral drugs to prevent spread of flu.
In fact, the authors of this study suggest focusing resources on that containment effort would probably be more valuable than drawing up plans to ban air travel once a pandemic has started.
Grounding all international air travel would create huge problems for the transport of essential goods and would decimate an already fragile industry.
The director of immunization and respiratory infections for the Public Health Agency of Canada said this study, along with two other recent modelling efforts, reinforces the belief of experts that grounding planes isn't an appropriate response.
"Shutting down plane travel is unlikely to be effective or sustainable because of the way influenza behaves," said Dr. Theresa Tam. Some diseases lend themselves to containment using travel restrictions - something like SARS, for instance, where only people showing symptoms were infectious and there was a long incubation period that allowed authorities to monitor people who'd been exposed.
But influenza is not one of them. Flu has a short incubation period, typically one to four days. And people who are incubating the disease can spread it before realizing they are sick.
The authors conclude that attempting to screen incoming air travellers for disease once a pandemic has started would also be a wasted effort, saying "such an intervention would have a negligible impact on the course of a pandemic once it was underway."
They suggested that rather than working on strategies to restrict travel in the early phases of a pandemic, public health authorities should focus their efforts on planning ways to slow spread within a community once a pandemic strain has arrived. School closures are considered one possible way to slow spread.