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The Effect of Stay-at-Home Orders on COVID-19 Infections in the United States

15 Pages Posted: 28 Apr 2020

See all articles by James H. Fowler

James H. Fowler

UC San Diego Division of Social Sciences; University of California, San Diego (UCSD) - Division of Infectious Diseases and Global Public Health

Seth Hill

University of California, San Diego (UCSD) - Department of Political Science

Remy Z. Levin

University of California, San Diego (UCSD) - Department of Economics

Nick Obradovich

Max Planck Society for the Advancement of the Sciences - Center for Humans and Machines

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Abstract

Background: In March and April 2020, public health authorities in the United States acted to mitigate transmission of and hospitalizations from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19). These actions were not coordinated at the national level, which raises the question of what might have happened if they were. It also creates an opportunity to use spatial and temporal variation to measure their effect with greater accuracy.

Methods: We combine publicly available data sources on the timing of stay-at-home orders and daily confirmed COVID-19 cases at the county level in the United States (N = 132,048). We then derive from the classic SIR model a two-way fixed-effects model and apply it to the data with controls for unmeasured differences between counties and over time. This enables us to estimate the effect of stay-at-home orders while accounting for local variation in factors like health systems and demographics, and temporal variation in national mitigation actions, access to tests, or exposure to media reports that could influence the course of the disease.

Findings: Mean county-level daily growth in COVID-19 infections peaked at 17.2% just before stay-at-home orders were issued. Two way fixed-effects regression estimates suggest that orders were associated with a 3.8 percentage point (95% CI 0.7 to 8.6) reduction in the growth rate after one week and an 8.6 percentage point (3.0 to 14.1) reduction after two weeks. By day 22 the reduction (18.2 percentage points, 12.3 to 24.0) had surpassed the growth at the peak, indicating that growth had turned negative and the number of new daily infections was beginning to decline. A hypothetical national stay-at-home order issued on March 13, 2020 when a national emergency was declared might have reduced cumulative county infections by 62.3%, and might have helped to reverse exponential growth in the disease by April 5.

Interpretation: Although stay-at-home orders impose great costs to society, delayed responses and piecemeal application of these orders generate similar costs without obtaining the full potential benefits suggested by this analysis. The results here suggest that a coordinated nationwide stay-at-home order may have reduced by hundreds of thousands the current number of infections and by thousands the total number of deaths from COVID-19. Future efforts in the United States and elsewhere to control pandemics should coordinate stay-at-home orders at the national level, especially for diseases for which local spread has already occurred and testing availability is delayed. Since stay-at-home orders reduce infection growth rates, early implementation when infection counts are still low would be most beneficial.

Funding Statement: None.

Declaration of Interests: The authors declare no competing interests.

Keywords: COVID-19; pandemic; public health

Suggested Citation

Fowler, James H. and Hill, Seth and Levin, Remy and Obradovich, Nicholas, The Effect of Stay-at-Home Orders on COVID-19 Infections in the United States (4/13/2020). Available at SSRN: https://ssrn.com/abstract=3576826 or http://dx.doi.org/10.2139/ssrn.3576826

James H. Fowler (Contact Author)

UC San Diego Division of Social Sciences ( email )

9500 Gilman Drive
Code 0521
La Jolla, CA 92093-0521
United States

HOME PAGE: http://jhfowler.ucsd.edu

University of California, San Diego (UCSD) - Division of Infectious Diseases and Global Public Health ( email )

La Jolla, CA
United States

HOME PAGE: http://jhfowler.ucsd.edu

Seth Hill

University of California, San Diego (UCSD) - Department of Political Science ( email )

9500 Gilman Drive
Code 0521
La Jolla, CA 92093-0521
United States

Remy Levin

University of California, San Diego (UCSD) - Department of Economics ( email )

9500 Gilman Drive
La Jolla, CA 92093-0508
United States

Nicholas Obradovich

Max Planck Society for the Advancement of the Sciences - Center for Humans and Machines ( email )

Berlin
Germany

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