Royal College of Surgeons in Ireland
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Social distancing causally impacts the spread of SARS-CoV-2: a U.S. nationwide event study

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journal contribution
posted on 2022-10-28, 16:20 authored by Louis Gagnon, Stephanie Gagnon, Jessica Lloyd

We assess the causal impact of social distancing on the spread of SARS-CoV-2 in the U.S. using the quasi-natural experimental setting created by the spontaneous relaxation of social distancing behavior brought on by the protests that erupted across the nation following George Floyd's tragic death on May 25, 2020. Using a difference-in-difference specification and a balanced sample covering the [- 30, 30] day event window centered on the onset of protests, we document an increase of 1.34 cases per day, per 100,000 population, in the SARS-CoV-2 incidence rate in protest counties, relative to their propensity score matching non-protest counterparts. This represents a 26.8% increase in the incidence rate relative to the week preceding the protests. We find that the treatment effect only manifests itself after the onset of the protests and our placebo tests rule out the possibility that our findings are attributable to chance. Our research informs policy makers and provides insights regarding the usefulness of social distancing as an intervention to minimize the spread of SARS-CoV-2. 


Smith School of Business Distinguished Faculty Fellowship at Queen’s University



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Published Citation

Gagnon L, Gagnon S, Lloyd J. Social distancing causally impacts the spread of SARS-CoV-2: a U.S. nationwide event study. BMC Infect Dis. 2022;22(1):787.

Publication Date

13 October 2022

PubMed ID



  • Undergraduate Research


BioMed Central


  • Published Version (Version of Record)