Next, we explored the impact of the 2-week winter school break implemented after the peak of the pandemic on July 16, using an age-structured mathematical model of influenza transmission tailored to the population of Peru (Text S1). The predicted reduction in the final epidemic size obtained by reducing the transmission rate within the student population (i.e., ,19 years) when R 0 = 1.6 and R 0 = 1.8 is shown in Figure H in Text S1 for various values of the percentage reduction of the transmission rate of the student population (20%-60%) and the timing of the start of the school closing period occurring a number of days after the epidemic peak. For an R 0 of 1.6, a reduction of 30% in the transmission rate among the student population yields a 4-10% reduction in the pandemic attack rate when the 22-day school closing period takes place 5-20 days after the epidemic peak. A higher R 0 value of 1.8 is associated with an even smaller reduction in the attack rate (4-7%). Overall we found that the reduction in the pandemic attack rate decreases significantly as R 0 increases.