The use of school closure strategies is controversial, mostly because of the lack of empirical evidence about the behavior of the population during the implementation of these policies. Still, in some regions of Russia reactive school closure policies are implemented every year to mitigate seasonal influenza. Over the course of the 2015-2016 influenza season, we performed a diary-based contact survey to estimate: i) human contact patterns both during regular school/working days and when schools/classes are closed as a consequence of the school closure policy; and ii) the effect of the school closure policy on the spread of influenza.

By combining micro- and macro-level sociodemographic data with the collected contact survey data, we developed an innovative hybrid survey-modeling framework to estimate the time-varying network of human social interactions. On the top of this network, we simulate a model of influenza spread.

We found a significant reduction of the number of contacts made by students and workers when the school closure policy is in place, which is not offset by the measured increase in the number of contacts between students and non-household relatives. We estimated that without the implemented reactive strategies the attack rate of the 2015-16 influenza season would have been 33% larger. More in general, our simulations suggest that gradual reactive school-closure policies based on monitoring student absenteeism rates are capable of mitigating the spread of both seasonal and pandemic influenza.

The collected individual contact diaries are openly available in section DATA.

The results of our analysis are published in M. Litvinova, Q.-H. Liu, E.S. Kulikov, M. Ajelli. Reactive school closure weakens the network of social interactions and reduces the spread of influenza. PNAS 116(27):13174-13181, 2019.