Fig. 2From: Measuring the potential of individual airports for pandemic spread over the world airline networkAEF and invasion threshold. Higher AEF is associated with a lower transmission rate needed to trigger pandemics (panel a), as well as shorter delay until the outbreak reaches pandemic status (panel b). In panel (b), the large dots mark the lowest transmission rate for which a pandemic occurred, for each city, and correspond to the points used to generate the regression line in panel (a). Cities are listed in order of increasing AEF. See also Table 1Back to article page