Fig. 2: Inferred introduction times and expansion of SECs.

a, ML phylogenetic tree of Spanish sequences indicating the identified SECs (inner circle), the Pango lineage (middle circle) and the NextStrain clade (outer circle). b, Range of dates for each ‘candidate transmission cluster’ identified within the SECs, and the most probable origin date (14 days before the first documented case). c, Time of the MRCA of each SEC is plotted, including the 95% HPD interval. First collected sample, and whether it is Spanish or non-Spanish, is indicated. d, SEC dispersion through the different regions of the country. Some SECs are restricted to one or two regions, while others have expanded through the complete territory.