Reopening businesses and risk of COVID-19 transmission

Ashley O'Donoghue,Frank J Defalco,Jennifer P Stevens,Manvi Madan,Aalok Thakkar,Tenzin Dechen,Whitney Pavlova,Michael Boals,Garba Moussa

doi:10.1038/s41746-021-00420-9

Abstract

The true risk of a COVID-19 resurgence as states reopen businesses is unknown. In this paper, we used anonymized cell-phone data to quantify the potential risk of COVID-19 transmission in business establishments by building a Business Risk Index that measures transmission risk over time. The index was built using two metrics, visits per square foot and the average duration of visits, to account for both density of visits and length of time visitors linger in the business. We analyzed trends in traffic patterns to 1,272,260 businesses across eight states from January 2020 to June 2020. We found that potentially risky traffic behaviors at businesses decreased by 30% by April. Since the end of April, the risk index has been increasing as states reopen. There are some notable differences in trends across states and industries. Finally, we showed that the time series of the average Business Risk Index is useful for forecasting future COVID-19 cases at the county-level (P < 0.001). We found that an increase in a county’s average Business Risk Index is associated with an increase in positive COVID-19 cases in 1 week (IRR: 1.16, 95% CI: (1.1–1.26)). Our risk index provides a way for policymakers and hospital decision-makers to monitor the potential risk of COVID-19 transmission from businesses based on the frequency and density of visits to businesses. This can serve as an important metric as states monitor and evaluate their reopening strategies.

Highlights

The United States has the highest number of confirmed COVID-19 cases in the world to date, with over 150,000 COVID-19-related deaths as of July 31, 20201
We found that the average Business Risk Index in a county was useful for forecasting positive COVID-19 cases in that county with a one-week lag (P < 0.001)
We developed a Business Risk Index to quantify the traffic and risk of COVID-19 transmission at businesses based upon the duration of visits and the density of visitors in the businesses

Summary

Introduction

The United States has the highest number of confirmed COVID-19 cases in the world to date, with over 150,000 COVID-19-related deaths as of July 31, 20201. A New York Times opinion piece by Baicker et al.[8] used cell-phone mobility data and found that gyms, full-service restaurants, fast-food restaurants, and nail salons had the highest number of visitors, and the longest average visit length in April 2019, prior to the pandemic. This suggests that there may be more opportunities for human-to-human contact at these locations during the pandemic. As businesses shut down and, more recently, reopened with more regulations to ensure social distancing and safety, these 2019 levels of traffic used in this opinion piece may no longer be a good indicator of reopening risk and scientific evidence examining the changing mobility patterns during the pandemic is needed

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