For the illustrative purposes, we chose values of 1.5, 2.5 and 3.5 for R, which encompass estimates proposed for previous pandemics [2, 3, 15] . The number of people within the infected source region was assumed reasonably small (5 million), and there was one flight per day traveling from the source region to the at-risk country carrying 400, 100 or 10 passengers. A higher number of travelers affects the delay only marginally, assuming the epidemic takes off in the source region (see Results). We assume a typical travel duration between attempted departure and possible arrival of 12 hours, but also examine the effect of varying this from 0-48 hours. The time to presentation following symptom onset is varied from 'immediately' to 'never presenting', with a time of 6 hours considered likely in the presence of an education campaign. The sensitivity of symptomatic screening is varied from 0-100%, with results presented for 0, 50 and 100% sensitivity.