China: Airport screening is of limited use

China's airport screening, which includes scanning all arriving passengers for fever using “noncontact thermal imaging” since late January and requiring passengers to report their health status on arrival, look reassuring but won't stop the spread of the novel coronavirus because experience with other diseases shows it's very rare for screeners to detect infected passengers (even where they exist) and it has little impact on the course of an outbreak when they do. Ben Cowling, an epidemiologist at the University of Hong Kong says that these measures delay, but do not prevent, a local epidemic. However, there can be benefits in evaluating and quizzing passengers before they board planes, since this prevents some sick or exposed passengers from traveling and early arrival screening can help gather contact information that can be used in case of a spread during a flight. However, in a paper Christos Hadjichristodoulou and Varvara Mouchtouri at the Uniersity of Thessaly suggest that screening may help head off more stringent travel restrictions and discourage some passengers exposed to diseases such as Ebola from travelling. 

Source: https://www.sciencemag.org/news/2020/03/why-airport-screening-wont-stop-spread-coronavirus