Figure 3
The impact of summer holiday on the transmission dynamics of influenza A (H1N1-2009). A. Comparison of the observed and predicted weekly counts of the estimated number of influenza cases in Japan from week 31 to 42. Grey bars are conditionally expected values during the summer school holiday, while white bars are the conditionally expected values during autumn semester. B. Numerical solutions of the number of infectious individuals in a hypothetical population of 100,000 individuals with initial condition (S0, I0, U0) = (99998, 1, 1). Baseline scenario is compared against intervention scenario under a short-lasting intervention. For both scenarios, assumed R(0) and mean generation time are 1.14 and 3 days, respectively. In the second scenario, the transmission rate is reduced by a factor α = 0.948 due to summer school holiday from time 0 to t1 (=50 days). Although heights of peak prevalence do not greatly differ from each other, the time to observe the peak is clearly delayed in the second scenario.