Last week I was searching the Internet for some COVID-19 statistic or other, and I came across a new CDC website. The site featured some numbers the federal government is using to model the spread of the epidemic. One in particular caught my eye: 0.4 percent, the “current best estimate” of the disease’s “case fatality rate.” The document also said that 35 percent of infections are asymptomatic, which suggests the infection fatality rate is just 0.26 percent.
These numbers struck me as low for several reasons. For one thing, the virus has already killed 0.2 percent of all New Yorkers, and obviously a much higher percentage of those who’ve actually been infected in the city. For another, if we’ve had 100,000 deaths nationwide and a CFR of 0.4 percent, that means we’ve had 25 million symptomatic cases; including cases without symptoms, more than 10 percent of the entire country has been infected, which seems out of sync with what we’re hearing from serology tests. Individual studies and reviews of the evidence tend to put the infection fatality rate somewhere around 0.5 to 1 percent, though there’s at least one dissenting review that puts it lower (while managing not to include any studies finding a fatality rate above 0.5 percent, of which there are plenty).
I put out a tweet expressing my confusion, and things spiraled quickly, as they often do on social media. A follower alerted the prominent biologist Carl Bergstrom, who wrote a thread criticizing the CDC’s numbers. The next morning he was featured in a CNN story about the issue. There have been many media reports since, with the narrative predictably varying from “Heroic Scientific Experts Hammer Corrupt CDC for Fake Low Fatality Rate” to “CDC Finally Admits COVID Is Basically Harmless.” (I exaggerate, but only a little.)
I don’t have a scorching hot take on the number. But I do want to know where it comes from, which is not clear from the site itself. It says the information is based on data about a month old and names the source “Preliminary COVID-19 estimates, CDC,” which I have not been able to locate (if indeed it refers to a specific document at all).
If the fatality rate of this thing is 0.26 percent, that is fantastic news. If the CDC has evidence this is the case, it should share it with the rest of us.