Reopening Schools in the Pandemic Did Not Increase COVID-19 Incidence and Mortality in Brazil
26 Pages Posted: 30 Mar 2021
Date Written: March 25, 2021
Background: School closures due to COVID-19 have left 1.6 billion students around the world without in-person classes for a prolonged period of time. To date, no study has documented whether reopening schools in developing countries during the pandemic causally increased aggregate COVID-19 incidence and mortality with appropriate counterfactuals.
Methods: We take advantage of the fact that 131 municipalities in São Paulo State, Brazil, reopened schools for in-person activities between October and December 2020, to estimate the causal effects of school reopening on municipal-level COVID-19 effective potential growth and deaths. We estimate treatment effects through a differences-in-differences strategy, comparing how outcomes evolved between municipalities that reopened schools and all others, before and after school reopening. We also estimate heterogeneous treatment effects by local characteristics. Last, we estimate the effects of school reopening on a local mobility index to shed light on the mechanisms behind its impacts on disease activity.
Findings: We find that school reopening did not increase COVID-19 incidence or mortality on average, up to 12 weeks after reopening. The counterfactual is critical for our conclusions: comparing only municipalities that reopened schools before and after reopening would lead us to conclude the opposite. Reopening schools did not affect disease activity even in poorer municipalities, in those with low-quality school infrastructure, with higher senior population share, or with higher baseline disease activity. We also find no effects of school reopening on the local mobility index.
Interpretation: While keeping schools open during the pandemic could still increase risks for school staff and students’ families, our findings suggest that it did not contribute to the aggregate disease activity. This was the case not only because schools typically represent only a small fraction of the overall municipal population, but also because counterfactual mobility during the pandemic was already substantial even in the absence of in-person classes – making the marginal health benefits of keeping schools closed negligible in the aggregate.
Note: Funding Statement: Research funded by the Inter-American Development Bank.
Declaration of Interests: GL and OLN received fees from the Inter-American Development Bank (IADB) for the design of this study. JC is an IADB staff member. CAB declares no competing interests.
Keywords: COVID-19; Development Economics; Schools reopening; Epidemiology
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