Fig. 3.

The age of outbreak occurrence associated to QX genotype is plotted over time as circles (randomly jittered to avoid graphical overlapping), whose radius is proportional to the number of events. A smoothed tendency line with confidence intervals is reported to summarize the general trend. The different phases (i.e. vaccination strategies) have been represented as solid (double vaccination) or dotted (Mass only vaccination) lines and numbered accordingly to the order reported in the manuscript. The time window considered ranges from the most ancient to the most recent sample.