Back to School: The Effect of School Visits During COVID-19 on COVID-19 Transmission
Schools across the United States and the world have been closed in an effort to mitigate the spread of COVID-19. However, the effect of school closure on COVID-19 transmission remains unclear. We estimate the causal effect of changes in the number of weekly visits to schools on COVID-19 transmission using a triple difference approach. In particular, we measure the effect of changes in county-level visits to schools on changes in COVID-19 diagnoses for households with school-age children relative to changes in COVID-19 diagnoses for households without school-age children. We use a data set from the first 46 weeks of 2020 with 130 million household-week level observations that includes COVID-19 diagnoses merged to school visit tracking data from millions of mobile phones. We find that increases in county-level in-person visits to schools lead to an increase in COVID-19 diagnoses among households with children relative to households without school-age children. However, the effects are small in magnitude. A move from the 25th to the 75th percentile of county-level school visits translates to a 0.3 per 10,000 household increase in COVID-19 diagnoses. This change translates to a 3.2 percent relative increase. We find larger differences in low-income counties, in counties with higher COVID-19 prevalence, and at later stages of the COVID-19 pandemic.
Funding provided by NIA K01AG061274 and the Conrad N. Hilton Foundation. We thank Castlight Health and SafeGraph for access to the data used in this study. Russell Hanson, Aaron Kofner, David Kravitz, Megan Pera, and Adrian Salas provided helpful data assistance. We thank Daniel Arnold, Timothy Brown, Dhaval Dave, Chrissy Eibner, Bryant Hopkins, Paul Koegel, Jonathan Ketcham, Maria Agustina Laurito, and Christine Mulhern for helpful comments. We also thank seminar participants at the RAND Education and Labor Brownbag. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.