Impacts of social distancing policies on mobility and COVID-19 case growth in the US

Wellenius, Gregory A.; Vispute, Swapnil; Espinosa, Valeria; Fabrikant, Alex; Tsai, Thomas C.; Hennessy, Jonathan; Dai, Andrew; Williams, Brian; Gadepalli, Krishna; Boulanger, Adam; Pearce, Adam; Kamath, Chaitanya; Schlosberg, Arran; Bendebury, Catherine; Mandayam, Chinmoy; Stanton, Charlotte; Bavadekar, Shailesh; Pluntke, Christopher; Desfontaines, Damien; Jacobson, Benjamin H.; Armstrong, Zan; Gipson, Bryant; Wilson, Royce; Widdowson, Andrew; Chou, Katherine; Oplinger, Andrew; Shekel, Tomer; Jha, Ashish K.; Gabrilovich, Evgeniy

Social distancing remains an important strategy to combat the COVID-19 pandemic in the United States. However, the impacts of specific state-level policies on mobility and subsequent COVID-19 case trajectories have not been completely quantified. Using anonymized and aggregated mobility data from opted-in Google users, we found that state-level emergency declarations resulted in a 9.9% reduction in time spent away from places of residence. Implementation of one or more social distancing policies resulted in an additional 24.5% reduction in mobility the following week, and subsequent shelter-in-place mandates yielded an additional 29.0% reduction. Decreases in mobility were associated with substantial reductions in case growth two to four weeks later. For example, a 10% reduction in mobility was associated with a 17.5% reduction in case growth two weeks later. Given the continued reliance on social distancing policies to limit the spread of COVID-19, these results may be helpful to public health officials trying to balance infection control with the economic and social consequences of these policies.