Although flight-based quarantining is effective in preventing the entry of infected travelers during the height of the epidemic, a substantial cumulative risk of initiation has already occurred before this from the handful of infectives that have slipped through undetected ( Figure 3B ). Hence, whilst the effect of border screening, particularly in conjunction with flight-based quarantining, on the daily probability of initiation is dramatic, its effect on the delay to initiation is much less pronounced ( Figure 3C ). Border screening, even with perfect sensitivity for detecting symptomatic cases, tends to increase D 1 , the time to an epidemic being initiated, by a matter of days to weeks. The time (D 2 ) from initiation (the arrival of the index case) to an epidemic reaching 20 concurrent cases within the at-risk country is adequately modeled using a shifted Gamma distribution ( Figure 4A ). The convolution of this right-skewed Gamma distribution with the left-skewed delaydistribution of D 1 (Figure 3C ) yields the distribution for D, the total delay until the epidemic reaches 20 cases in the at-risk country ( Figure 4B ). The distribution of D is approximately symmetrical. The effect of border screening on the total delay D is quite modest, though sensitive to how screening is implemented. For example, with R = 1.5 and 400 travelers per day, 100% sensitive screening with individual-based removal increases the median delay from 57 to 60 days ( Figure 4B ). Flight-based quarantining would extend the median delay to 70 days. In general, the added delay arising from flight-based quarantining is about four-fold that arising from individual-based removal.