Cause-Specific Excess Mortality in the US During the COVID-19 Pandemic

The COVID-19 pandemic was a significant shock to United States mortality, and it is important to understand how the pandemic impacted other causes of death. We estimated monthly excess mortality in the US by cause of death, age, and sex, for official deaths at ages 15 and older. Data come from the CDC Wonder Multiple Cause of Death database. We used a compositionally robust Generalized Additive Model (GAM) to estimate expected mortality counts in March 2020-December 2022 for eight causes of death: accidents, cardiovascular diseases, cancer, diabetes, influenza and pneumonia, substance-related (drugs and alcohol), suicide, and residual (including COVID-19 related deaths). Analyses were stratified by sex and 15-year age groups from 15-29 to 75+. Excess mortality was calculated as observed deaths minus expected deaths. From March 2020 to December 2022, we estimated 1 298 763 total excess deaths (95% CI: 1 226 542 to 1 370 804). While there were fewer deaths than expected due to some causes like flu/pneumonia and suicide, the largest number of excess deaths, excluding COVID-19, were attributed to cardiovascular diseases (115 765 deaths, 95% CI: 98 697 to 133 783) and substance use (86 637 deaths, 95% CI: 79 273 to 93 690). Percent excess substance-related mortality was high across all ages, while percent excess from cardiovascular diseases was highest at midlife ages. Some of these excess cardiovascular deaths were likely due to undercounted COVID-19 deaths, but others may reflect indirect impacts of the pandemic on healthcare utilization or longer-term effects of COVID-19 infections.