Fig. 4: Sankey plots summarizing the viral flow into Portuguese Health Administration regions.

Left. The plot shows the relative number of transitions between countries of origin and different regions in Portugal. For summaries that show all transitions to and from all connected locations, we refer to the Supplementary Data 4. Right. The plot shows the relative number of infections generated by introductions from countries of origin and different regions in Portugal. For summaries that show the size of all introductions to and from all connected locations, we refer to the Supplementary Data 5. For both panels, for graphics simplicity, we present the eleven countries linked with most introductions (left) and relative number of infections generated (right), estimated across phylogenies inferred for the whole dataset, i.e., including both Pango lineages A and B (thin – low proportion of number/size of viral introductions attributed to this source; thick – high proportion of number/size of viral introductions attributed to this source). We note that there is no temporal order for the transitions involved.