Enacting national social distancing policies corresponds with dramatic reduction in COVID19 infection rates.

Daniel J Mcgrail,Raghu Kalluri,Kathleen M Mcandrews,Jianli Dai,Chris T Bauch

doi:10.1371/journal.pone.0236619

Daniel J Mcgrail, Raghu Kalluri + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0236619

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Abstract

The outbreak the SARS-CoV-2 (CoV-2) virus has resulted in over 6.5 million cases of COVID19, greatly stressing global healthcare infrastructure. Lacking medical prophylactic measures to combat disease spread, many nations have adopted social distancing policies in order to mitigate transmission of CoV-2. While mathematical models have suggested the efficacy of social distancing to curb the spread of CoV-2, there is a lack of systematic studies to quantify the real-world efficacy of these approaches. Here, we first demonstrate that implementation of social distancing policies in US states corresponded with a reduction in COVID19 spread rates, and that the reduction in spread rate is proportional to the average change in mobility. We validate this observation on a worldwide scale by analyzing COVID19 spread rate in 134 nations with varying social distancing policies. Globally, we find that social distancing policies significantly reduced the COVID19 spread rate, with resulting in an estimated 65% reduction (95% CI = 39–80%) in new COVID19 cases over a two week time period. These data suggest that social distancing policies may be a powerful tool to prevent spread of COVID19 in real-world scenarios.

Highlights

COVID19, caused by the novel coronavirus SARS-CoV-2 (CoV-2) [1], was declared a global pandemic by the World Health Organization on March 11th 2020
In order to assess the efficacy of social distancing policies in the United States, we began by quantifying the COVID19 spread rate as defined by an exponential growth function both before and after social distancing policies were enacted
Analysis of COVID19 spread rates may be complicated by numerous features, including population demographics and densities, travel rates, variations in testing accessibility, weather patterns, and likely many more parameters yet to be identified

Summary

Introduction

COVID19, caused by the novel coronavirus SARS-CoV-2 (CoV-2) [1], was declared a global pandemic by the World Health Organization on March 11th 2020. As of June 5th 2020, the disease had spread to over 6.5 million cases worldwide, straining the global healthcare infrastructure, and is rapidly becoming a leading cause of death [2]. Medical interventions to address COVID19 are lacking both in the context of prophylactic vaccination approaches, as well as pharmaceutical interventions to treat infected patients. Some countries such as Singapore have demonstrated the feasibility of contact tracing when sufficient testing capacities are available to quarantine exposed individuals and contain disease spread [3]. Contact tracing may not always be possible to directly implement due to lack of testing availability, lack of infrastructure/funding to perform contact tracing, imprecise data a patient’s interactions while

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