Excess deaths in the United States during the first year of COVID-19

Accurately determining the number of excess deaths caused by the COVID-19 pandemic is hard. The most important challenge is determining the counterfactual count of baseline deaths that would have occurred in its absence. Flexible estimation methods were used here to provide this baseline number and plausibility of the resulting estimates was evaluated by examining how changes between baseline and actual prior year deaths compared to historical year-over-year changes during the previous decade. Similar comparisons were used to examine the reasonableness of excess death estimates obtained in prior research. Total, group-specific and cause-specific excess deaths in the U.S. from March 2020 through February 2021 were calculated using publicly available data covering all deaths from March 2009 through December 2020 and provisional data for January 2021 and February 2021. The estimates indicate that there were 649,411 (95% CI: 600,133 to 698,689) excess deaths in the U.S. from 3/20–2/21, a 23% (95% CI: 21%–25%) increase over baseline, with 82.9% (95% CI: 77.0% - 89.7%) of these attributed directly to COVID-19. There were substantial differences across population groups and causes in the ratio of actual-to-baseline deaths, and in the contribution of COVID-19 to excess mortality. Prior research has probably often underestimated baseline mortality and so overstated both excess deaths and the percentage of them attributed to non-COVID-19 causes.