Fig. 3

Determination of mean seeding time (ST) and mean doubling time (DT) and ST/DT Model sensitivity analysis. a With seeding number (SN) set to 12 cases for all countries and seeding time (ST) for each country calculated as the number of days required to reach SN = 12, early epidemic stage doubling time (DT) for each country was calculated as the mean number of days required to observe case doubling to 24, 48, and then 96 cases. All 20 countries were plotted on the ST/DT Model coordinate plane and overall mean ST was found to be 18 days (vertical line) and overall mean DT was found to be 5 days (horizontal line). b For sensitivity analysis, later epidemic stage DT was calculated as the mean number of days for each country to observe case doubling to 192, 384, and 768 cases. The countries with the largest changes from early to later stage epidemic were Australia, Malaysia, and Thailand, all of which moved from moderately low risk to high risk. Viet Nam also had a marked reduction in DT but remained moderately low risk. All countries in the moderately high risk quadrant moved closer to the mean DT line but did not cross over into the low risk quadrant. The only country that did not move at all (ie, had no change in DT) was Switzerland