Fig. 4: Land-based regional connectivity drives introduction risk during the period of travel restrictions.

A Estimated introduction (importation) Intensity Index (II) for 2020, divided into the Middle East and the remaining (Global, non-Middle Eastern). Countries grouped by region, except Middle Eastern countries in the bottom panel, which are country-level. Legend in A applies to C. B Contribution of land and air travel to II in (A) for highest ranked regional countries. C Temporal synchrony between introductions estimated from genomic data (across all downsampling strategies and randomizations) and the weekly rolling average estimated introduction index (II) across the four regions summarizing the countries with the 20 highest individual-level II in (A) for the period prior to travel restrictions (top panel) and the period travel restrictions were in place (bottom panel). The normalized time series for the genomic estimates of introduction are depicted in light gray, with a line per seed and downsampling strategy, and the estimated introduction index (II) for each region are annotated in color. D The dynamic time warp distance between the query genomic estimate and each region’s III across all downsampling strategies and randomizations for the period prior to travel restrictions. E The dynamic time warp distance between the query genomic estimate and each region’s II across all downsampling strategies and randomizations for the period travel restrictions were in place.