Fig. 1

Reference scenario in the absence of interventions. All simulations shown are based on reference parameter values (reported in Sec. Methods) and initialized with 10 infectious individuals. We ran 100 stochastic realizations of the model and based our results on those simulations that caused an epidemic (i.e., more than 150 total symptomatic cases). a Simulated mean weekly incidence of new symptomatic cases per 1000 individuals (line) and 95 % CI (area). b Simulated mean weekly school absenteeism (line) and 95 % CI (area). c Simulated infection attack rate (median, 50 % and 95 % CI). d Simulated mean infection attack rate by age (line) and 95 % CI (area). The subpanel shows the distribution (median, 50 % and 95 % CI) of the simulated infection attack rate by age group (boxplots); dots represent infection attack rates (difference between post- and pre-pandemic seroprevalence) as reported in serosurvey data on the 2009 H1N1 influenza pandemic in Italy [17, 22]