A Note on Yesterday’s Reports of a 3.4% COVID-19 Fatality Rate

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Yesterday a number of major news organizations (including the Post, CNBC and others) reported that the WHO had released a new COVID-19 mortality rate of 3.4% which was significantly higher than earlier estimates.

As reported, this new information was at least significantly misleading.

What the head of the WHO, Dr. Tedros Adhanom Ghebreyesus, said was this: “Globally, about 3.4 percent of reported Covid-19 cases have died. By comparison, seasonal flu generally kills far fewer than 1 percent of those infected.”

This is a more technical and limited statement than those press reports suggested. It takes the number of deaths to date and divides it by the number of reported and/or confirmed cases. The key phrase is “reported COVID-19 cases.” We know however that especially outside of China the number of infections is significantly underreported. For instance, in an extreme case, there are currently 128 confirmed/reported cases in the United States and 8 deaths. No one thinks there are not significantly more than 128 cases in the United States. We simply haven’t found most of them yet.

(Note that it is also possible that the mortality rate in the United States is higher to date because it took root most quickly in an assisted living facility of people who were at the highest risk from the disease.)

This appears to be the case to varying degrees in many countries around the world. The extent to which it is the case in China is more complicated and uncertain.

When you try to clarify something like this lots of people think you’re trying to downplay the threat. I’m not. Most estimates of COVID-19 lethality range from between 2% and 3% at the high end to between 1% and .5% at the low end. That means an infection that ranges anywhere from 5 times to 30 times of the lethality of the flu. In other words, an extremely dangerous respiratory infection.

What is probably reasonable to say is that the lethality of this disease, once understood over time with a broad array of data, will likely be lower than that 3.4% and that this statement was intended more as a current state of play – known cases versus deaths – than an upward revision on the inherent lethality of the virus.

[ed.note: As you know, I am not an epidemiologist or a doctor. But I have consulted with experts on this specific question and believe this is a more accurate way to look at this report. If you are a reader with relevant expertise and think otherwise please let me know.]

Here is some additional instructive information. Some of the most aggressive testing in the world has taken place in South Korea. They currently have over 5,300 infections. But there’s little question that a significant amount of that number, compared to other countries, is driven by how many people they’re testing.

Their just released demographic and mortality breakdown is instructive.

Key points. Over 5300 cases. No fatalities under 30. Very few under 50. Overall death rate among **confirmed** cases .6%. Heavy concentration of mortality over age 70. (The range of lethality over different ranges is broadly comparable to the breakdown over more than 70,000 infections in China.)

We don’t know the ‘true’ death rate is .6% anymore than we know it’s 3.4%, though that appears closer to the mortality rate in China outside of Wuhan. Even a ‘true’ rate is a bit of a misnomer since mortality is highly dependent on the standard of care, how overwhelmed a health system at the time of illness, and how good the health care system is in a given country in general, etc.

This is a very dangerous disease, many times more deadly than the flu, especially for older people and those with underlying medical problems. I don’t think we learned it was more deadly yesterday than scientists thought the day before.

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