by Marianne Freiberger
Submitted by mf344 on November 18, 2014
Eurostar
Screening is in place at the Eurostar terminal in London, St. Pancras. Image: Purple.
With five UK airports, as well as the Eurostar Terminal, now screening travellers arriving from high-risk countries for Ebola, the question remains whether this measure is effective. You can think of reasons for and against it, and people have. But the point is that you don't need to rely on speculations to make decisions about preventative measures against diseases. There are ways of measuring their impact that are based on evidence.
A recent study published in the British Medical Journal found that "an entrance screening policy will have no meaningful effect on the risk of importing Ebola into the UK" (assuming that people who are already obviously sick aren't allowed to board a plane). And since the effort is expensive and disruptive, the authors suggest the money would be better spent in West Africa, where it could prevent a humanitarian crisis of "frightening proportions".
Their argument is straight-forward. "For Ebola the incubation period is very long," explains Adam Kucharski of the London School of Hygiene and Tropical Medicine, a colleague of the authors of the study. "If someone gets on a plane without symptoms, they would have to become symptomatic on that flight. The study showed that because the average time between exposure to the virus and becoming symptomatic is around a week, your chances of catching people using those screening methods are incredibly low (around 7%). Introducing those screening measures was very much a political, rather than a scientific, decision.