I keep seeing opinions saying that the CFR of the coronavirus is ~2% — and not to worry, that’s probably a higher end estimate because we’re missing lots of mild cases. I wish that were true, but let me explain why that simply not the case.‬ And why even if it was, you should still be tremendously concerned.





Hospitalization and ICU Rate

Firstly , let’s talk about the hospitalization rate. Every reputable source agrees that 10–20% of cases require hospitalization, and ~5% require an IUC. Even if we stopped the whole discussion right here that would be enough info for tremendous concern. There is not anywhere *near* to that number of ICU beds or ventilators in the county. If this becomes widespread- which experts now agree it almost certainly will — at least 5% of people will need, ‬and largely be unable to get, significant medical care. Consider that right now 9% of Italian cases are in the ICU.





Let me quote from a 2006 NYT article talking about the shortage of ventilators for a hypothetical bird flu pandemic:‬

Right now, there are 105,000 ventilators, and even during a regular flu season, about 100,000 are in use… In a national emergency, he said, “it will come down to some really thin cuts on a scoring system.” “Families are going to be told, ‘We have to take your loved one off the ventilator even though, if we could keep him on it for a week, he might be fine,’ “ he went on. “How do you think that’s going to go over? It’s going to be a nightmare.”





No Evidence to Suggest We’re Missing a Ton of Mild Cases

Now let’s talk about the myth that there are a ton of mild cases that we haven’t detected — which would drive down the case fatality rate (CFR). The WHO has said that they see NO evidence for this. To quote:

“One of the hopes of people watching China’s coronavirus outbreak was that the alarming picture of its lethality is probably exaggerated because a lot of mild cases are likely being missed. But on Tuesday, a World Health Organization expert suggested that does”“So I know everybody’s been out there saying, ‘Whoa, this thing is spreading everywhere and we just can’t see it, tip of the iceberg.’ But the data that we do have don’t support that,”





The Case Fatality Rate

Last, but not least, let’s talk about that 2.3% CFR rate that’s being parroted around everywhere. This is based on a study by the Chinese CDC. Characteristics of and Important Lessons From the Coronavirus Disease 2019 (COVID-19) Outbreak in China. In the study they show how they have 44,672 cases and 1023 deaths at the time of writing the paper. 1023/44672 = 2.3%. There is a name for this methodology, it’s referred to as the Naïve CFR, and everyone that it grossly underestimates the true CFR.





Think about it for a moment, they’re saying that they have ~44k cases and 1023 dead right now. It assumes that no additional people will die who are now infected. A totally wrong assumption. But don’t take my word for it — here’s a quote from a recent study on the novel coronavirus:

The time from the illness onset to death is also comparable to SARS [15], and the 15–20-day mean delay indicates that a crude estimation of the ratio of the cumulative number of deaths to that of confirmed cases will tend to result in an underestimation of the case fatality risk, especially during the early stage of epidemic spread.[emphasis added]

Or take a look at this study Methods for Estimating the Case Fatality Ratio for a Novel, Emerging Infectious Disease which looks and how different methodologies perform in estimating CFR. The Naïve CFR (simple estimate 1 in the study) grossly underestimated SARS — calculating as low as 2.5% CFR when the true number was ~13%

The methodology that was accurate was to look at the resolved cases (simple estimate 2). CFR = deaths/ (deaths + recoveries).





And there are other studies that use more reasonable methodologies and get a more reasonable CFR.









Summary

1. The hospitalization rate is enough to result in a terrible CFR once the healthcare system is overwhelmed. (See Wuhan)

2. There is no evidence that a *huge* number of mild cases are being missing which would drive the CFR down by orders of magnitude.

3. The 2.3% CFR is completely disingenuous





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