County-Level Estimates of Excess Mortality Associated with COVID-19 in the United States

Abstract Background The COVID-19 pandemic in the U.S. has been largely monitored on the basis of death certificates containing reference to COVID-19. However, prior analyses reveal that a significant percentage of excess deaths associated with the pandemic were not directly assigned to COVID-19. Methods In the present study, we estimate a generalized linear model of expected mortality in 2020 based on historical trends in deaths by county of residence between 2011 and 2019. We use the results of the model to generate estimates of excess mortality and excess deaths not assigned to COVID-19 for 1,470 county-sets in the U.S. representing 3,138 counties. Results During 2020, more than one-fourth of U.S. residents (91.2 million) lived in counties where less than 75% of excess deaths were assigned to COVID-19. Across the country, we estimated that 439,698 excess deaths occurred in 2020, among which 86.7% were assigned to COVID-19. Some regions (Mideast, Great Lakes, New England, and Far West) reported the most excess deaths in large central metros, whereas other regions (Southwest, Southeast, Plains, and Rocky Mountains) reported the highest excess mortality in nonmetro areas. The proportion assigned to COVID-19 was lowest in large central metro areas (79.3%) compared to medium or small metros (87.4%), nonmetro areas (89.4%) and large fringe metros (95.2%). Regionally, the proportion of excess deaths assigned to COVID-19 was lowest in the Southeast (81.1%), Far West (81.2%), Southwest (82.6%), and Rocky Mountains (85.2%). Across the regions, the number of excess deaths exceeded the number of directly assigned COVID-19 deaths in the majority of counties. The exception to this was in New England, which reported more directly assigned COVID-19 deaths than excess deaths in large central metro areas, large fringe metros, and medium or small metros. Conclusions Across the U.S., many counties had substantial numbers of excess deaths that were not accounted for in direct COVID-19 death counts. Estimates of excess mortality at the local level can inform the allocation of resources to areas most impacted by the pandemic and contribute to positive protective behavior feedback loops (i.e. increases in mask-wearing and vaccine uptake).