Fever Screening at Airports
I’ve seen the IR screening guns at several airports, primarily in Asia. The idea is to keep out people with Bird Flu, or whatever the current fever scare is. This essay explains why it won’t work:
The bottom line is that this kind of remote fever sensing had poor positive predictive value, meaning that the proportion of people correctly identified as having fever was low, ranging from 10% to 16%. Thus there were a lot of false positives. Negative predictive value, the proportion of people classified by the IR device as not having fever who in fact did not have fever was high (97% to 99%), so not many people with fevers will be missed with the IR device. Predictive values depend not only on the accuracy of the device but also how prevalent fever is in the screened population. In the early days of a pandemic, fever prevalence will be very low, leading to low positive predictive value. The false positives produced at airport security would make the days of only taking off your shoes look good.
The idea of airport fever screening to keep a pandemic out has a lot of psychological appeal. Unfortunately its benefits are also only psychological: pandemic preparedness theater. There’s no magic bullet for warding off a pandemic. The best way to prepare for a pandemic or any other health threat is to have a robust and resilient public health infrastructure.
Lots more science in the essay.
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