In 2019, nearly 81% of U.S. adults owned a smartphone capable of transmitting location data, and many U.S. prediction models are using, or plan to use, cell phone location data as a tool to help summarize human behavior as a means to understand disease spread and inform policy. However, evidence to support cell phone location data as a marker of the decline in the growth rate of cases is lacking. Initial work described associations between aggregate location data and social distancing; however, a study of associations with disease growth rates while considering regional confounding factors is lacking.

In a recent study, urban counties with higher populations and a higher number of cases per unit population saw a larger relative decline in activity outside of the place of residence and a greater increase in residential activity after the institution of stay-at-home orders. An increase in workplace activity and reduction in residential activity over time suggests waning adherence to the orders over time. This increase in phone activity in different counties is associated with case growth rates at 5, 10, and 15 days later, suggesting that these measures may be useful in monitoring and identifying areas at risk for more rapid rates of growth in new cases during the pandemic.

Perhaps the most important observation of this study was that a decrease in activity at the workplace, transit stations, and retail locations and an increase in activity at the place of residence was associated with a significant decline in COVID-19 cases at 5, 10, and 15 days. There you have it. This is one study of so many but honestly, it says volumes! Stay home unless you absolutely cannot! Protect yourself, your loved ones, and your community! Stay the course, stay strong, stay well, mask up, and stay tuned!