Effects of Temporal Factors in School Closure Policy for Mitigating the Spread of Influenza

It has been under debates whether school closure is effective in mitigating the outbreak of influenza. To better address the problem, we develop an individual-based simulation model based on the real-life contact data in Singapore. By conducting extensive simulations on the model, we evaluate the impacts of temporal factors, namely the trigger threshold and duration, on the effectiveness of school closure as a mitigation policy. Our observations show that there exists an upper bound of the duration of school closure, further extension beyond which will not bring additional benefits to suppressing the attack rate and peak incidence. We also show that, for school closure with a relatively short duration (< 6 weeks), it is more effective to start it with a relatively longer delay from the first day of infection; if the duration of school closure is long (> 6 weeks), however, it is better to start it as early as reasonable. Our studies reveal the critical importance of timing in school closure, especially in cost-cautious situations. The studies also demonstrate the great potential of a properly developed individual-based simulation model in evaluating various disease control policies.