Table 1.

Mixed-effects negative binomial model examining the impact of social distancing on COVID-19 mortality (deaths per 100,000 people) in US counties between the period of the report of the first case of COVID-19 and May 31, 2020.

Variables	Incidence rate ratio (95% CI)	P value
Average proportion of mobile phone usage outside of home between March and May 2020	1.18 (1.12-1.24)	<.001
Average proportion of mobile phone usage outside of home in February 2020	0.90 (0.86-0.94)	<.001
Population density (100 persons per square mile)	1.02 (1.01-1.04)	<.001
Days between the report of the first confirmed case of COVID-19 and May 31, 2020	1.03 (1.02-1.04)	<.001