GENEVA - The World Health Organisation on Tuesday stressed that border screenings "don't work" in detecting passengers who may be infected with swine flu, even as many countries intensified airport checks.
"If a person has been exposed or infected... the person might not be symptomatic at the airport," WHO spokesman Gregory Hartl told journalists.
"Border controls don't work. Screening doesn't work."
Many Asian countries hit by the Severe Acute Respiratory Syndrome have set up thermal scanners at airports to screen for passengers who may be feverish.
Amid the swine flu scare, these countries have restarted these checks.
Officials at US airports, land ports and border crossings have also begun screening travellers and questioning those who show flu symptoms, Homeland Security Secretary Janet Napolitano said.
But Hartl said that research since the SARS outbreak in 2003 in Asia had shown that border controls were of little use in tackling the spread of flu.
"We learn as we go on. SARS was a huge learning experience for all of us."
While yielding few public health benefits, such travel controls caused huge economic disruptions, said Hartl.
"It became extremely clear after SARS that the efficacy of border checks far underweighed the economic disruption," he said.
"So there was much more economic disruption by these measures than there was public health benefit. In public health terms, it didn't work. So we don't want to repeat something that didn't work."
Even though the WHO's pandemic preparedness guidance documents suggest that in phase 4, countries should consider implementing exit screening, Hartl explained that such "screening" refers to giving information on the flu situation and does not include scanning for fever.
"Fever monitoring doesn't work because you don't get the cases which are still in incubation," he said.
Restrictions on travel hit the airline industry particularly hard during the SARS epidemic.
International Air Transport Association (IATA) chief Giovanni Bisignani also warned Tuesday that the swine flu threat could have a "significant" impact on air traffic.
"It is still too early to judge what the impact of swine flu will have on the bottom line. But it is sure that anything that shakes the confidence of passengers has a negative impact on the business," he said.
"And the timing could not be worse given all of the other economic problems airlines are facing."
Keiji Fukuda, acting WHO assistant director-general for health, security and the environment late Monday said that given the widespread nature of the virus, all corners of the world are at potential risk from the virus.
"I think that in this age of global travel where people move around in airplanes so quickly, there is no region to which this virus could not spread," said Fukuda.
Nevertheless, he stressed that the UN health agency did not recommend closing borders or restricting travel.
"With the virus being widespread... closing borders or restricting travel really has very little effect in stopping the movement of this virus," he said.