Alliance for Pandemic Preparedness

May 7, 2020

Impact of Policy Interventions and Social Distancing on SARS-CoV-2 Transmission in the United States

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  • Dreher et al. conducted a state-level analysis using regression models with primary outcomes defined as the average effective reproductive number (Rt) in the week after the state reached 500 cases and doubling time from 500 to 1000 cases.  
  • After controlling for population density, GDP, and health metrics, they found that having a stay-at-home order in place at the time of the 500th case was significantly associated with a lower average Rt the following week and had a very strong association with the probability of Rt<1.  
  • Doubling time for cases was significantly longer for states with an early stay at home order (HR=0.35), as was the doubling time for deaths for states with more time spent at home (HR=0.18).  

Dreher et al. (May 6, 2020). Impact of Policy Interventions and Social Distancing on SARS-CoV-2 Transmission in the United States. Pre-print downloaded May 7 from https://doi.org/10.1101/2020.05.01.20088179