Model-driven mitigation measures for reopening schools during the COVID-19 pandemic

Reopening schools is an urgent priority as the COVID-19 pandemic drags on throughout much of the world. To explore the risks associated with returning to in-person learning and the value of mitigation measures in a school setting, we use the stochastic, network-based SEIRS+ epidemiological modeling platform to simulate SARS-CoV-2 transmission in schools. Because children and adolescents differ both in disease susceptibility and in patterns of social interaction, we use distinct models of SARS-CoV-2 transmission for primary and secondary school settings. We find that a number of mitigation measures may prove useful, particularly when community prevalence is low. Student cohorting, in which students are divided into two separate populations that attend in-person classes on alternating schedules, can reduce both the likelihood and the size of outbreaks. Proactive testing of teachers and staff once or twice a week can help catch introductions early, before they spread widely through the school. Especially in secondary schools, once- or twice- weekly testing amongst students should also be considered to further reduce the likelihood of a large outbreak amongst the full population. Vaccinating teachers and staff protects these individuals and may also have a disproportionate protective effect on the outbreak potential in primary and secondary schools when vaccines block SARS-CoV-2 transmission in addition to symptoms. Other mitigation strategies, including mask-wearing, social distancing, and increased ventilation, remain a crucial component of any reopening plan.