Thursday, March 10, 2011

Thermal scanning for flu

If there is an influenza pandemic then initial attempts at isolating the outbreak, or prevent its entry into particular countries, may involve the use of infrared thermal image scanners (ITIS) at airports to detect people with elevated body temperatures characteristic of influenza. We saw this in the 2009 H1N1 (Swine Flu) pandemic. Analysis suggests that countries that adopted the policy managed to delay disease entry for 7-12 days compared to countries that did not: Entry screening to delay local transmission of 2009 pandemic influenza A (H1N1). Of course there may be other differences between these two types of countries. Correlation is not causation...

A paper in PLoS ONE in January this year, Thermal Image Scanning for Influenza Border Screening: Results of an Airport Screening Study, looked at a sample of 1275 airline passengers who agreed to be screened, have their temperature actually measured and give a respiratory sample. Six of the travellers had a fever and thirty of the travellers tested positive for influenza. But none of the influenza-positive travellers had a temperature high enough to be considered in the fever group!

Our findings therefore suggest that ITIS is unlikely to be effective for entry screening of travellers to detect influenza infection with the intention of preventing entry of the virus into a country.

I'm sure we'll see more of these thermal scanners in airports in future pandemics even if they are fairly useless. Why? Because it makes it look like somebody is doing something (even if it is useless). Just like the rest of airport security

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