Figure 3

Connecting hierarchy with epidemic features and mitigation efforts. Shown are the 22 cities in the United States, as of June 14, 2020 in terms of the pandemic situation. Cities in pale yellow have already peaked, while infections continue to grow in those marked in red. The figure suggests the extent of spread is strongly correlated with centralization. (a) Average observed \(R_{\text {eff}}\) over three weeks after the onset of 100 cases as a function of \(\Phi\), namely \(R_{early}\). Initial observed transmission increased with centralization. (b) Accumulated number of reported new cases per capita two weeks before the maximum incidence \(I_{\text {max}}\). In (c), \(\Phi\) versus observed relative decrease in total flow. Mobility reductions were much more drastic in hierarchical cities. (d) Synchronization of mobility reduction and contagion spread among city counties measured through the Pearson coefficient of plots as those shown in Fig. 2g–i for Atlanta, Chicago and NYC. Response to mitigation was more sensitive in cities with higher \(\Phi\).