Effectiveness of airport screening at detecting travellers infected with 2019-nCoV

Billy Quilty; Sam Clifford; Stefan Flasche; Rosalind M Eggo

We assume that the time of starting travel is randomly and uniformly distributed between the time of infection and twice the expected time to severe disease; however, we only consider those travellers who depart before their symptoms worsen to the point that they would seek hospital care 6 . We simulate travellers with individual incubation period, time from onset to severe disease, flight start times and detection success at exit and entry screening according to the screening sensitivities ( Figure 3 ). We consider only the travel of infected individuals (not the proportion of travellers who are infected) and therefore assume a screening specificity of 100%. An individual will be detected at exit screening if their infection is not asymptomatic, their departure time exceeds their incubation period, and their stochastic exit screening success indicates detection. An individual will be detected at entry screening if their infection is not asymptomatic, their incubation period ends after their departure but before their arrival, they have not been detected at exit screening, and their entry screening success indicates detection. Entry screening detections are further divided into detection due to severe symptoms and detection of mild symptoms via equipment such as thermal scanners. We used 10,000 bootstrap samples to calculate 95% confidence intervals.