A Year of Coronavirus: How Deadly Was 2020 Compared to Other Years?
More complete data paints a clearer picture of overall mortality
M.G. Sunde
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Although it has not been widely discussed in the media, SARS-CoV-2 has been with us for well over a year. Researchers in California began to suspect that the virus arrived in the U.S. earlier than previously thought when they found that, starting in early December, the number of respiratory complaints was far higher than numbers seen during previous years.
Subsequent studies confirmed those suspicions. An analysis of blood samples in Italy showed that many individuals had already been infected and developed antibodies as early as September 2019. And a similar study, in which blood samples from nine U.S. states were analyzed, found evidence that the virus was already widespread in December 2019.
So, with 2020 now behind us, and more complete data in hand, it is worth examining how mortality for the year compares with that of previous years in order to gain a better perspective of the impact of the virus.
To account for age distributions and the relative number of events for populations across a range of years, researchers and government agencies such as the CDC typically compare deaths using age-adjusted mortality. Fortunately, age-adjusted mortality data for 1900 to 2018 is already available from the National Center for Health Statistics (NCHS).
Patching in the subsequent two years is possible using additional recently published data for 2019 and 2020 from the NCHS. Following the methods used by the CDC to calculate post-1999 death rates, the 2000 U.S. standard population can then be used to calculate the age-adjusted mortality for 2019 and 2020. Thus, the age-adjusted mortality for 1900 to 2020 is given in the chart below.
The turquoise bar, highlighted on the far right, depicts the 2020 death rate, which was 834.3 per 100,000 persons. To help with comparisons, the 2020 rate is also plotted across the entire series (orange line). While this is an increase from the 2019 rate of 715.2, it is lower than all other years on record for the U.S. from 2003 (highlighted in green) and prior.
For comparative purposes, the 2003 rate was 843.5, and the highest recorded rate was 2541.6 in 1918 (over three times higher than the 2020 rate). (Somewhat interestingly, the 1918 rate associated with the severe influenza epidemic that year was only slightly higher than that of multiple other years of the early 20th century.) While the 2020 data will continue to be updated (there is some lag), the basic finding presented here will remain largely unchanged (the rate will remain roughly similar to 2002 or 2003).
Age-adjusted death rates for the U.S. (1900 to 2020)
So it can be seen that, while the 2020 death rate was quite low in historical terms, it was higher than what has been observed during recent years. However, it remains to be seen what proportion of these additional deaths resulted from pandemic-related disruptions to healthcare, isolation of the elderly, and upticks in deaths related to causes such as drug use and suicide.
For example, a study published in the Journal of the American Medical Association showed that VA hospital admissions for life-threatening conditions dropped by 42% early in the pandemic, and excess Alzheimer’s and dementia deaths for the year were thought to number over 26,000 as of September.
In addition, while early excess death estimates among people under 25 were low (841 in the U.S. as of early October), suicide rates appear to have increased as disruptions to everyday life have dragged on. A study in Japan showed a 49% increase among adolescents during the second pandemic wave, and the CDC acknowledged that there were “markedly elevated prevalences of reported adverse mental and behavioral health conditions associated with the COVID-19 pandemic” in a recent report.
School districts around the U.S. have also seen concerning increases in suicides and mental health issues among school children. Adding to these other issues is the fact that 2020 saw an unprecedented increase in homicides, with over 19,000 Americans dying as a result of gun-related incidents.
Finally, a recent CDC report indicated that, while the vast majority of excess deaths occurred among the elderly, the greatest relative increase in deaths occurred in the 25 to 44 age group. The data suggest that deaths in this younger age cohort are probably not related to COVID-19, but are more likely attributable to some of the causes previously discussed.
Overall, there was not a particularly high level of mortality during 2020 in historical terms. Yet there was a significant uptick relative to recent years, during which mortality levels had been unprecedentedly low. The question that remains to be answered is: what proportion of those deaths resulted from the reaction to the virus, and what proportion resulted from the virus itself? A clearer picture will develop as more data on the underlying causes of these deaths is released during the coming months and years.
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