The effect of school closures and reopening strategies on COVID-19 infection dynamics in the San Francisco Bay Area: a cross-sectional survey and modeling analysis

Abstract

Background Large-scale school closures have been implemented worldwide to curb the spread of COVID-19. However, the impact of school closures and re-opening on epidemic dynamics remains unclear. Methods We simulated COVID-19 transmission dynamics using an individual-based stochastic model, incorporating social-contact data of school-aged children during shelter-in-place orders derived from Bay Area (California) household surveys. We simulated transmission under observed conditions and counterfactual intervention scenarios between March 17-June 1, and evaluated various fall 2020 K-12 reopening strategies. Findings Between March 17-June 1, assuming children <10 were half as susceptible to infection as older children and adults, we estimated school closures averted a similar number of infections (13,842 cases; 95% CI: 6,290, 23,040) as workplace closures (15,813; 95% CI: 9,963, 22,617) and social distancing measures (7,030; 95% CI: 3,118, 11,676). School closure effects were driven by high school and middle school closures. Under assumptions of moderate community transmission, we estimate that fall 2020 school reopenings will increase symptomatic illness among high school teachers (an additional 40.7% expected to experience symptomatic infection, 95% CI: 1.9, 61.1), middle school teachers (37.2%, 95% CI: 4.6, 58.1), and elementary school teachers (4.1%, 95% CI: -1.7, 12.0). Results are highly dependent on uncertain parameters, notably the relative susceptibility and infectiousness of children, and extent of community transmission amid re-opening. The school-based interventions needed to reduce the risk to fewer than an additional 1% of teachers infected varies by grade level. A hybrid-learning approach with halved class sizes of 10 students may be needed in high schools, while maintaining small cohorts of 20 students may be needed for elementary schools. Interpretation Multiple in-school intervention strategies and community transmission reductions, beyond the extent achieved to date, will be necessary to avoid undue excess risk associated with school reopening. Policymakers must urgently enact policies that curb community transmission and implement within-school control measures to simultaneously address the tandem health crises posed by COVID-19 and adverse child health and development consequences of long-term school closures.

Using an Agent-Based Model to Assess K-12 School Reopenings Under Different COVID-19 Spread Scenarios – United States, School Year 2020/21

“…The results show similar trends for the Baseline, 80% in-person learning, 40% 2-day and alternating week, and offsite school scenarios with Fewer Open Workplaces and More Open Workplaces assumptions for both regional and national simulations. All the partial onsite learning scenarios delay the epidemic peak and flatten the curve for Fewer Open Workplaces, which is consistent with previous studies on school closures [13][14][15][16] (Figure 2, 3). However, for More Open Workplaces, the peak for most scenarios is spread around three weeks regardless of school reopening scenario and the impact of hybrid school reopenings is reduced.…”

“…The copyright holder for this preprint this version posted October 13, 2020. ; https://doi.org/10.1101/2020.10.09.20208876 doi: medRxiv preprint the spread of COVID-19 [15]. In addition, hybrid approaches to learning, such as capping the inperson classroom size, may be effective in reducing transmission [14,16] and provide a balance approach between supporting education while limiting the spread of COVID-19.…”

Impacts of K-12 school reopening on the COVID-19 epidemic in Indiana, USA

“…This is due in part to our assumption that asymptomatic and 11 symptomatic infections contribute similarly to transmission [26,67,37,36,68], and in part to our model's ability to capture chains of transmission within schools and extending out into the community. Our study echoes several modeling studies in emphasizing the importance of reducing school capacity to impede transmission [61,62,63,64,72]. Taking all this evidence together, those deciding on strategies to safely reopen schools should strongly consider operating at reduced capacity and strictly enforcing face-mask adherence.…”

Optimal Control of the COVID-19 Pandemic with Non-pharmaceutical Interventions

“…Whereas a previous optimal control analysis of pandemic influenza (Shim 2013) suggested that age-specific optimal controls were all relatively similar, recent work on COVID-19 (Richard et al 2020;Gondim and Machado 2020) suggests that optimal controls should be higher for older age-groups due to their higher risk of severe disease and death. Inclusion of age structure is important for other reasons too, such as realistically capturing transmission dynamics (Britton et al 2020) and accounting for age-specific interventions, such as school closures (Head et al 2020). Additional limitations that affect our model's suitability for making future predictions include its deterministic nature and the rudimentary calibration procedure that we performed, which was sufficient to provide a basis for qualitative analyses but that would need refinement for application of our model to inference or forecasting.…”