What do people think of this preprint from March 13th?
- R0=~5 in Wuhan in January (pre-containment measures)
- Infection fatality rate=~0.1% (several orders of magnitude smaller than the crude CFR estimated at 4.19%)
- ~2 million infections in Wuhan on Jan 23rd / ~20% of people infected
The authors are very reputable (GScholar profile first author, senior author, also quoted in the NYT).
If this is true, might there be many more (asymptomatic) cases everywhere now than people think?
"Recently more evidence suggests that a substantial fraction of the infected individuals with the novel coronavirus show little if any symptoms, which suggest the need to reassess the transmission potential of this emerging disease"
True, but Diamond Princess is full of oldies, and, despite South Korea massive testing, there might be selection bias - I guess people would only get tested if they had some symptom or contact with other infected persons (perhaps you're referring a more specific study?). Notice that, if the science study claiming 86% of the cases in Wuhan were undocumented were right, this would already imply a fatality rate of about 0.6%, below South Korea estimates.
Yet, I agree the fatality rate is surprisingly low, and it's just a statistical model.
Diamond princess is important because they did 100% testing so it gives us an idea of asymptomatic : symptomatic ratio. The result was roughly 1:1, nothing like 50:1 or whatever this paper suggests. The science study with 6:1 is at least plausible if you account for symptomatics who weren't identified.
If South Korea hadn't managed to test the majority of their cases then it is unlikely that they would have managed to reduce their infection rate so dramatically - their quarantine measures aren't massively strict although I think the population are self-enforcing good practice pretty well. I doubt that Wuhan death rates could be below South Korean rates due to the acknowledged overcrowding in Wuhan. Again, 0.6% is kind of plausible, the model here (0.1%) isn't.