Modeling the impact of school reopening on SARS-CoV-2 transmission using contact structure data from Shanghai

Abstract

Background: Mathematical modeling studies have suggested that pre-emptive school closures alone have little overall impact on SARS-CoV-2 transmission, but reopening schools in the background of community contact reduction presents a unique scenario that has not been fully assessed.

Methods: We adapted a previously published model using contact information from Shanghai to model school reopening under various conditions. We investigated different strategies by combining the contact patterns observed between different age groups during both baseline and "lockdown" periods. We also tested the robustness of our strategy to the assumption of lower susceptibility to infection in children under age 15 years.

Results: We find that reopening schools for all children would maintain a post-intervention R₀ < 1 up to a baseline R₀ of approximately 3.3 provided that daily contacts among children 10-19 years are reduced to 33% of baseline. This finding was robust to various estimates of susceptibility to infection in children relative to adults (up to 50%) and to estimates of various levels of concomitant reopening in the rest of the community (up to 40%). However, full school reopening without any degree of contact reduction in the school setting returned R₀ virtually back to baseline, highlighting the importance of mitigation measures.

Conclusions: These results, based on contact structure data from Shanghai, suggest that schools can reopen with proper precautions during conditions of extreme contact reduction and during conditions of reasonable levels of reopening in the rest of the community.

Keywords: COVID-19; Pandemic; SARS-CoV-2; SEIR model; SIR model; Schools.

Fig. 1

Effects of school reopening during community “lockdown.” Post-intervention R₀ as a function of baseline R₀ under various conditions are shown. Dashed black line: Baseline, represents all contact patterns pre-pandemic. Solid orange line: School closure alone, represents community pre-pandemic contact patterns but with contacts among children 0–19 years removed to simulate full school closure. Solid green line: Full “lockdown,” represents full contact suppression during pandemic conditions. Solid blue line: Full school reopening, represents full “lockdown” conditions but with re-incorporation of all contacts among children 0–19 years according to baseline contact patterns to simulate return to full school attendance. Interrupted blue line: Mixed reopening model, simulates the effect of re-incorporating full contact patterns for children 0–9 years with reduction in contacts in children 10–19 years to 33% of baseline. Dashed blue line: Reopen < 10 years only, simulates the effect of re-incorporating baseline contact patterns for children 0–9 years only

Fig. 2

Effects of school reopening based on differing rates of susceptibility to SARS-CoV-2 infection in children relative to adults. Post-intervention R₀ as a function of baseline R₀ under various estimates of susceptibility to SARS-CoV-2 infection in children < 15 years are shown. Dashed black line: Baseline, represents all contact patterns pre-pandemic. Solid black line: Mixed reopening model, simulates the effect of re-incorporating full contact patterns for children 0–9 years with reduction in contacts in children 10–19 years to 33% of baseline. Starting from this condition, blue lines represent a range of estimates of susceptibility to SARS-CoV-2 infection in children relative to adults: 40% (dotted blue line), 45% (dashed blue line), 50% (interrupted blue line), and 60% (solid blue line)

Fig. 3

Effects of school reopening along with community reopening. Post-intervention R₀ as a function of baseline R₀ under various conditions are shown. Dashed black line: Baseline, represents all contact patterns pre-pandemic. Solid black line: Mixed reopening model, simulates the effect of re-incorporating full contact patterns for children 0–9 years with reduction in contacts in children 10–19 years to 33% of baseline. Starting from this condition, blue lines represent the effects of restoration of contact frequency in the rest of the community (i.e. community reopening) to 20% of baseline (dotted blue line), 30% of baseline (dashed blue line), 40% of baseline (interrupted blue line), or 60% of baseline (solid blue line)