Modeling the Risk of In-Person Instruction During the Coronavirus Disease 2019 Pandemic

We use mathematical modeling and simulation to evaluate the safety of in-person instruction in university classrooms under different interventions. We find that, for the Delta variant of COVID-19, requiring masking when more than 90% of students are vaccinated is safe and easy to implement, without needing to assign fixed seats or improving the ventilation in classrooms. Our model supported Cornell University to safely conduct in-person instruction in fall 2021.