Impact of Social Distancing Measures on Coronavirus Disease Healthcare Demand, Central Texas, USA

Xutong Wang; Remy F. Pasco; Zhanwei Du; Michaela Petty; Spencer J. Fox; Alison P. Galvani; Michael Pignone; S. Claiborne Johnston; Lauren Ancel Meyers

Disclosures

Emerging Infectious Diseases. 2020;26(10):2361-2369. 

In This Article

Abstract and Introduction

Abstract

Social distancing orders have been enacted worldwide to slow the coronavirus disease (COVID-19) pandemic, reduce strain on healthcare systems, and prevent deaths. To estimate the impact of the timing and intensity of such measures, we built a mathematical model of COVID-19 transmission that incorporates age-stratified risks and contact patterns and projects numbers of hospitalizations, patients in intensive care units, ventilator needs, and deaths within US cities. Focusing on the Austin metropolitan area of Texas, we found that immediate and extensive social distancing measures were required to ensure that COVID-19 cases did not exceed local hospital capacity by early May 2020. School closures alone hardly changed the epidemic curve. A 2-week delay in implementation was projected to accelerate the timing of peak healthcare needs by 4 weeks and cause a bed shortage in intensive care units. This analysis informed the Stay Home-Work Safe order enacted by Austin on March 24, 2020.

Introduction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appeared in Wuhan, China, during December 2019, and coronavirus disease (COVID-19) caused by this virus was declared a pandemic on March 11, 2020, by the World Health Organization.[1] As of June 24, a total of 193 countries, areas, or territories had reported 9,129,146 confirmed COVID-19 cases and 473,797 deaths. Substantial outbreaks have occurred in India, Russia, Brazil, and the United States; the United States has the highest cumulative confirmed number of cases and deaths.[2]

The United States reported its first imported SARS-CoV-2 case from Wuhan on January 20, in Washington,[3] 6 days ahead of California[4] and 40 days ahead of New York, New York;[5] the first locally infected cases were reported on February 28.[6] As of June 24, all 50 states had reported confirmed cases, 48 had reported community spread, and cumulative confirmed COVID-19 cases were 2,336,615 and deaths were 121,117.[7] Surges in COVID-19 hospitalizations have compromised local healthcare systems in New York[8] and Seattle.[9]

Beginning in March 2020, states and cities implemented extensive social distancing measures to contain the spread of SARS-CoV-2, including school closures, limits on mass gatherings, shelter-in-place orders, travel restrictions, and bans on nonessential commercial activities. By early April, 45 states had issued a statewide shelter-in-place order or ≥1 city-level stay-at-home order, affecting >316 million persons. As of June 25, all measures have expired or relaxed.[10] The timing of the orders varied; California was the first state to enact strict orders on March 19 and South Carolina the last on April 7.[10] These measures dramatically slowed the pace of the pandemic during April and May, but confirmed COVID-19 cases and hospitalizations have been increasing since early June, particularly in Arizona, Florida, Texas, and California.[11]

As COVID-19 emerged into a global threat, we took a national pandemic influenza model that was built through a pandemic preparedness contract with the Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA) and adapted it to model the spread and control of COVID-19 within and between 217 US cities. We used this model to project the potential effects of school closures coupled with social distancing, in terms of reducing cases, deaths, hospitalizations, intensive care unit (ICU) visits, and ventilator needs, on local, regional, and national scales. We have focused our analysis on Austin, which is the capital of Texas and the fastest growing city in the United States, as a representation of major US metropolitan areas. The scenarios and inputs (e.g., epidemiologic parameters) were determined in consultation with CDC and the Regional Healthcare System Executive Council of the Austin–Travis County Emergency Operations Command.

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