"CDC Estimated a One-Year Decline in Life Expectancy in 2020. Not So — Try Five Days"

From Dr. Peter Bach at StatNews:

The Centers for Disease Control and Prevention made headlines last week when it announced that Covid-19 had reduced the average life expectancy of Americans in 2020 by a full year…. [But t]he pandemic's appalling toll could not have reduced life span by nearly that much. My own estimate is that when Covid-19's ravages in 2020 are averaged across the country's entire population, we each lost about five days of life.

The CDC's mistake? It calculated life expectancy using an assumption that is assuredly wrong, which yielded a statistic that was certain to be misunderstood….

People understood [the CDC's report] to mean that Covid-19 had shaved off a year from how long each of us will live on average. That is, after all, how people tend to think of life expectancy. The New York Times characterized the report as "the first full picture of the pandemic's effect on American expected life spans."

But wait. Analysts estimate that, on average, a death from Covid-19 robs its victim of around 12 years of life. Approximately 400,000 Americans died Covid-19 in 2020, meaning about 4.8 million years of life collectively vanished. Spread that ghastly number across the U.S. population of 330 million and it comes out to 0.014 years of life lost per person. That's 5.3 days. There were other excess deaths in 2020, so maybe the answer is seven days lost per person.

No matter how you look at it, the result is a far cry from what the CDC announced.

It's not that the agency made a math mistake. I checked the calculations myself, and even went over them with one of the CDC analysts. The error was more problematic in my view: The CDC relied on an assumption it had to know was wrong….

Read the whole thing, which strikes me as persuasive (and which explains the almost certainly incorrect assumption on which the CDC relied); and while I'm far from an expert on the subject, I ran it by some professors who are much more knowledgeable than I am, and they generally agreed with Dr. Bach's analysis.