Using temperature scanners in airports to try to identify and block entry of sick travellers during a disease outbreak is unlikely to achieve the desired goal, a report by French public health officials suggests.
Their analysis, based on a review of studies on temperature screening efforts like those instituted during the 2003 SARS outbreak, says the programs may be of limited use in the early days of a flu pandemic, when governments might be tempted to order screening of incoming travellers to try to delay introduction of the illness within their borders.
The authors, from France's Health Watch Institute, said the available scientific data suggests there is little benefit to airport temperature screening when the incidence of disease is low, as it was with SARS and as it would be expected to be in the very early days of a pandemic.
"Because public perceptions are important, policy-makers may feel some pressure to use NCIT" -- non-contact infrared thermometers -- "but the decision making process should not ignore the poor scientific evidence on NCIT's efficacy to delay the introduction of a novel influenza strain," they wrote.
One of the key figures in Toronto's SARS containment effort agreed with the conclusion, saying temperature screening was more about optics than about actually preventing the spread of disease.
"I think actually that probably is a large part of it. Sort of a sign that you're aware and you're trying to do something, whether or not it actually works," said Dr. Donald Low, head of microbiology at Toronto's Mount Sinai Hospital.
The report's conclusions are drawn primarily from studies of fever screening programs set up in hospitals. That's because the few studies conducted on airport screen programs for SARS and one for dengue fever in Taiwan did not contain enough data to assess how effective they might be to screen for a fever caused by any infection.
The findings were published in the most recent issue of Eurosurveillance, the weekly infectious diseases journal produced by the European Centre for Disease Prevention and Control in Stockholm.
The publication comes nearly six years to the day after the World Health Organization first warned that China's Guangdong province was reporting an outbreak of an unidentified diseases be named severe acute respiratory syndrome or SARS.
Nearly 8,100 people around the world went on to catch the disease; 774 of them died, 44 of them in Canada.
During the SARS outbreak a number of countries, including Canada, introduced airport temperature screening. In some cases it was an attempt to keep out the sick. In Canada's case, it was also an effort -- adopted under pressure from the WHO -- to ensure sick Canadians didn't ignite new outbreaks abroad.
A 2004 study on Canada's airport screening efforts showed that 4.6 million travellers were screened between May and November of 2003. Only 1,435 had an elevated temperature and none of those people had SARS.
Even a federal government report at the time acknowledged the machines were better at assuaging public jitters than detecting disease.
"While the scanners are not necessary from a (SARS) detection perspective, their value lies in their ability to build public confidence in the screening program," the report said.
Low noted that because it can take several days for an incubating infection to produce symptoms, a one-time temperature screening will miss people who are infected but are not yet feeling ill.
"The trouble with screening is this false sense of security," he said.
Low said governments would be better off trying to educate people about why it is important -- for their own health and the health of others -- that they seek medical assistance if they become ill while travelling.
"I think probably that approach is the most reasonable," he said.
