Impact of Population Growth and Aging on Estimates of Excess U.S. Deaths During the COVID-19 Pandemic, March to August 2020

Abstract

Background: Excess death estimates quantify the full impact of the coronavirus disease 2019 (COVID-19) pandemic. Widely reported U.S. excess death estimates have not accounted for recent population changes, especially increases in the population older than 65 years.

Objective: To estimate excess deaths in the United States in 2020, after accounting for population changes.

Design: Surveillance study.

Setting: United States, March to August 2020.

Participants: All decedents.

Measurements: Age-specific excess deaths in the United States from 1 March to 31 August 2020 compared with 2015 to 2019 were estimated, after changes in population size and age were taken into account, by using Centers for Disease Control and Prevention provisional death data and U.S. Census Bureau population estimates. Cause-specific excess deaths were estimated by month and age.

Results: From March through August 2020, 1 671 400 deaths were registered in the United States, including 173 300 COVID-19 deaths. An average of 1 370 000 deaths were reported over the same months during 2015 to 2019, for a crude excess of 301 400 deaths (128 100 non-COVID-19 deaths). However, the 2020 U.S. population includes 5.04 million more persons aged 65 years and older than the average population in 2015 to 2019 (a 10% increase). After population changes were taken into account, an estimated 217 900 excess deaths occurred from March through August 2020 (173 300 COVID-19 and 44 600 non-COVID-19 deaths). Most excess non-COVID-19 deaths occurred in April, July, and August, and 34 900 (78%) were in persons aged 25 to 64 years. Diabetes, Alzheimer disease, and heart disease caused the most non-COVID-19 excess deaths.

Limitation: Provisional death data are underestimated because of reporting delays.

Conclusion: The COVID-19 pandemic resulted in an estimated 218 000 excess deaths in the United States between March and August 2020, and 80% of those deaths had COVID-19 as the underlying cause. Accounting for population changes substantially reduced the excess non-COVID-19 death estimates, providing important information for guiding future clinical and public health interventions.

Primary funding source: National Cancer Institute.

Visual Abstract.. Impact of Population Growth and Aging on Excess U.S. Deaths During COVID-19

Estimates of excess mortality during the coronavirus disease 2019 (COVID-19) pandemic provide an important metric for quantifying deaths due to COVID-19 as well as those indirectly caused by COVID-19. The aging of the population, however, results in a rise in the expected number of deaths over time, and when not taken into account, excess mortality attributed to the pandemic may be overestimated. This study updates recent estimates for excess mortality by accounting for the aging of the population.

Figure 1.. Changes in age-specific U.S. population estimates and average annual deaths compared with the average number of deaths in the preceding 5 years, 2015 to 2020. Top.

U.S. population size, by age group and year, 2015 to 2020. Bottom. Annual deaths versus the average from the 5 previous years. Black bars indicate the number of deaths in a given year (that is, 2015, 2016, 2017, 2018, 2019, and 2020). Gray bars represent the average number of deaths for the 5 years before that year (that is, 2010–2014, 2011–2015, 2012–2016, 2013–2017, 2014–2018, and 2015–2019). Deaths in 2020 are limited to January through August and divided into COVID-19 deaths, unclassified deaths, and all other deaths. COVID-19 = coronavirus disease 2019.

Figure 2.. Data based on the CDC's provisional release of death certificate data for 1 March to 31 August 2019 and 2020, and complete death certificate data for 2015 to 2018, by age group.

CDC = Centers for Disease Control and Prevention; COVID-19 = coronavirus disease 2019. Top. Total excess deaths, calculated by using 2 approaches: unadjusted (gray bars) and adjusted (black bars) for the growth and aging of the U.S. population. Middle. Provisional number of COVID-19 deaths among persons aged 15 years and older. Between 1 and 9 COVID-19 deaths occurred in persons younger than 14 years in at least 1 of the months; thus, exact counts were suppressed by the CDC. Bottom. Total non–COVID-19 excess deaths unadjusted (gray bars) and adjusted (black bars) for the growth and aging of the U.S. population. Deaths among persons younger than 15 years are all assumed to be non–COVID-19 deaths, because COVID-19 deaths were suppressed in these age groups.

Figure 3.. Excess U.S. total and non–COVID-19 deaths, March to August 2020 by month, based on Centers for Disease Control and Prevention provisional release data.

Gray bars represent excess death estimates without adjustment for population changes, and black bars represent excess death estimates with adjustment for population changes. COVID-19 = coronavirus disease 2019.

Figure 4.. Excess U.S. cause-specific deaths, March to August 2020, by month, among persons aged 25 to 64 years and those aged 65 years and older.

Bars represent the number of deaths in 2020 compared with 2015 to 2019, after adjustment for population changes. COVID-19 = coronavirus disease 2019.