The general consensus on mortality due to COVID-19 is that it falls most heavily on people who are more impacted by aging: poor immune function when it comes to defense against pathogens; high levels of chronic inflammation that create a greater susceptibility to the way in which SARS-CoV-2 kills people; existing chronic disease; and a mortality rate that is already high even setting aside the pandemic. When younger people die due to the virus, in much smaller numbers, it is where they share these characteristics of inflammation, deficient immune systems, and chronic disease. This level of morbidity is unusual in younger individuals, but very prevalent in the old.
In today's open access commentary we see that COVID-19 mortality in older people is becoming comparable to that of the major age-related conditions, such as cancer. Those killed by COVID-19 are largely people with greater degrees of frailty and a shorter remaining life expectancy. We might see mortality fall significantly in the next few years, after the present pandemic mortality subsides due to the combination of vaccination and immunity to this virus. An appreciable fraction of those individuals who would have survived to die of non-communicable age-related conditions in 2021 or 2022 are dying now.
As to the numbers themselves, COVID-19 appears to continue to be on track to be at the worse end of the expected 3 to 6 times multiple of a bad influenza year: 300,000 deaths in the US versus 60,000 for the 2017-2018 influenza season. While there are numerous lessons to be taken from the past year regarding the behavior of highly regulated organizations and services, none of which are likely to be heeded, the most important lesson for the long term is that (a) old people are vulnerable to infection precisely because they have a failing immune system, and (b) there are many clear and obvious research projects that offer the potential to rejuvenate the aged immune system. Regrowing the thymus, restoring hematopoietic stem cell function, clearing out worn and damaged immune cells, and so forth. A great deal more funding and attention should be given to these lines of research.
A helpful approach to put the effects of the pandemic in context is to compare COVID-19-related mortality rates with the leading causes of death that, under ordinary circumstances, would pose the greatest threat to different age groups. The conditions listed in the table include the three leading causes of death in each of the 10 age groups from infancy to old age. Using data from the Centers for Disease Control and Prevention, the table shows mortality rates for these conditions during the period of March through October 2018 (the most recent year for which detailed cause-of-death data are available) with COVID-19 mortality rates during March through October 2020.
The table shows that by October 2020 COVID-19 had become the third leading cause of death for persons aged 45 through 84 years and the second leading cause of death for those aged 85 years or older. Adults 45 years or older were more likely to die from COVID-19 during those months than from chronic lower respiratory disease, transport accidents (eg, motor vehicle fatalities), drug overdoses, suicide, or homicide. In contrast, for individuals younger than age 45 years, other causes of death, such as drug overdoses, suicide, transport accidents, cancer, and homicide exceeded those from COVID-19.
Between November 1, 2020, and December 13, 2020, the 7-day moving average for daily COVID-19 deaths tripled, from 826 to 2430 deaths per day, and if this trend is unabated will soon surpass the daily rate observed at the height of the spring surge (2856 deaths per day on April 21, 2020). As occurred in the spring, COVID-19 has become the leading cause of death in the United States (daily mortality rates for heart disease and cancer, which for decades have been the two leading causes of death, are approximately 1700 and 1600 deaths per day, respectively). With COVID-19 mortality rates now exceeding these thresholds, this infectious disease has become deadlier than heart disease and cancer, and its lethality may increase further as transmission increases with holiday travel and gatherings and with the intensified indoor exposure that winter brings.