Reopening Businesses and Risk of COVID-19 Transmission

ImportanceThe United States has the highest number of confirmed COVID-19 cases in the world, with over 150,000 COVID-19-related deaths as of July 31, 20201. The true risk of a COVID-19 resurgence as states prepare to reopen businesses is unknown.ObjectiveTo quantify the potential risk of COVID-19 transmission in business establishments by building a risk index for each business that measures transmission risk over time.DesignThis retrospective case series study uses anonymized cell phone GPS data to analyze trends in traffic patterns to businesses that may be potentially high-risk from January 2020 to June 2020.SettingMassachusetts, Rhode Island, Connecticut, New Hampshire, Vermont, Maine, New York, and California.Participants1,272,260 businesses within 8 states from January 2020 – June 2020.Exposure(s)We monitored business traffic before the pandemic, during the pandemic and after early phases of reopening in 8 states.Main OutcomeOur primary outcome is our business risk index. The index was built using two metrics: visitors per square foot and the average duration of visits. Visitors per square foot account for how densely visitors are packed into businesses. The average duration of visits accounts for the length of time visitors are spending in a business.ResultsPotentially risky traffic behaviors at businesses decreased by 30% by April. Since the end of April, the risk index has been increasing as states reopen. On average, it has increased between 10 to 20 percentage points since April and is moving towards pre-pandemic levels of traffic. There are some notable differences in trends across states and industries.ConclusionOur 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. Traffic is slowly moving towards pre-pandemic levels. This can serve as an important metric as states monitor and evaluate their reopening strategies.