In many international airports, information is provided to travellers from affected regions recommending action if they develop symptoms on or after arrival [13-16]. Some countries, for example Japan, also require incoming passengers to complete forms detailing their past and future travel in order to aid tracing [17]. Due to the duration of the incubation period of 2019-nCoV infection, we find that exit or entry screening at airports for initial symptoms, via thermal scanners or similar, is unlikely to prevent passage of infected travellers into new countries or regions where they may seed local transmission.