Why have mortality rates among young adults spiked during the COVID pandemic?

This is a followup to my previous posts on the general topic of changes in mortality rates in America during the COVID pandemic. The striking thing about these changes is that the percentage increase in mortality rates among young adults has been greater than the percentage increase in mortality rates among the elderly, even though COVID mortality is so strongly correlated with increasing age.

In fact COVID mortality explains more than all of the increased mortality rate among the elderly, as mortality rates from other causes among the elderly have fallen during the pandemic. Meanwhile official COVID death totals explain relatively little of the mortality increase among young adults, yet that mortality increase has, in percentage terms, been about two to three times higher than the mortality increase among the elderly.

So obviously something besides COVID mortality, or at least official COVID mortality, is going on here.

To explore just what, I drilled way down into the specific mortality stats for 25-34 year olds over the last 12 months for which these numbers are available (spring 2020 through spring 2021, i.e., the first 12 months of the pandemic in the USA).

Here’s what I found:

All-cause mortality in this cohort rose by 40.4/100K over this twelve-month period. This produced the highest 12-month mortality for this cohort since the early 1950s, and indeed a mortality rate that was 65% (!) higher than the all-cause mortality rate in this cohort 20 years ago. (All-cause mortality among 25-34 year olds crept up gradually between 2003 and 2019, rising by a total of 23% over this time, before the massive leap last year).

Here’s the breakdown of the official causes of the increase over the last year:

COVID:  0 to 6.4. (15.8% of increase)

Drug overdose:  34.8 to 47.3 (31% of the increase)

Firearm injury:  17.9 to 23.6 (14.1% of the increase)

Homicide:  11.4 to  16.3  (12.1% of the increase)

Unintentional injuries:  52.7 to 71.3 (46% of the increase)

Now there’s some double counting here, because firearm injuries are collectively a subset of homicide, suicide, and unintentional injury, and drug overdoses are almost completely a subset of unintentional injuries. A further complication is that the drug overdose data aren’t for exactly the same period, since the 12-month rate isn’t available for the last two quarters in this analysis, because of data collection issues.

Still, if we just count the increase in unintentional injuries, COVID, and homicide we get: 18.6 + 6.4 + 4.9+ :  29.9 of 40.4  (74% of the 40.4/100K increase in all-cause mortality).

If we look at all other major causes of death where there was any statistical change at all we see:

Cancer  7.9 to 7.6

Chronic liver disease and cirrhosis: 2.4 to 4.0

Chronic lower respiratory disease:  0.7 to 0.8

Diabetes:  2.0 to 2.7

Heart disease:  7.6 to 8.7

HIV: 1.0 to 1.1

Hypertension:  0.2 to 0.4

Influenza and pneumonia: 1.0 to 0.7

Kidney disease:  0.6 to 0.7

Suicide:  17.5 to 18.3

4.1 total increase, i.e. these account for 10.1% of the total rise in all-cause mortality.

So this analysis accounts for 84% of the increase in all-cause mortality in this cohort. Note that official COVID deaths account for a fairly small fraction of that overall increase, and that even if you assume that all 16% of the missing increase in all-cause mortality is due to undiagnosed COVID, a full two-thirds of the overall increase in mortality among 25-34 year old adults in the last 12 months would still be due to other causes.

So the pandemic has been terrible for young adults in terms of increasing mortality, but apparently not primarily because of COVID directly, but because of secondary effects of the pandemic, especially in regard to drug overdoses and homicide, i.e., categories that somewhat overlap with Case’s and Deaton’s concept of “deaths of despair.”