Projections for first-wave COVID-19 deaths across the US using social-distancing measures derived from mobile phones

On March 26, 2020, the Institute for Health Metrics and Evaluation (IHME) at the University of Washington released a website that forecasts coronavirus disease (COVID-19) healthcare demand and mortality for all states in the United States. In light of the popular appeal of the IHME model and considerable scrutiny from the scientific community, we have developed an alternative curve-fitting method for forecasting COVID-19 mortality throughout the US. Our model is similar in spirit to the IHME model, but different in two important details. First, for each US state, we use local data from mobile-phone GPS traces made available by SafeGraph to quantify the changing impact of social-distancing measures on "flattening the curve." Second, we reformulated the approach in a generalized linear model framework to correct a statistical flaw that leads to the underestimation of uncertainty in the IHME forecasts. The incorporation of real-time geolocation data and several key modifications yields projections that differ noticeably from the IHME model, especially regarding uncertainty when projecting COVID-19 deaths several weeks into the future.