Figure 6.

Relative contribution of national vs. international transmission events to the Delta (A) and Omicron (B) epidemics. The variant migration events across the border (from California toward Mexico and from Mexico toward California in blue and orange respectively) accounted for 3.4% and 23% of all inferred migration events for Delta and Omicron, respectively. Migration events within California and within Mexico are shown in red and green. See Supplementary Figure S9 for a description of these contributions over time.