Genealogical tree and skyline plots of coalescent statistics for 1270 world-wide samples of HA sequences of influenza A (H3N2). The tree shown represents the maximum posterior tree sampled over the course of the MCMC analysis. Vaccine strains are shown on the tree as colored points. For coalescent statistics, TMRCA, diversity and N
τ, solid lines represent mean values and gray outlines represent 95% credible intervals across MCMC replicates. TMRCA, diversity and N
τ are measured in units of years.