tl;dr: Someone wrote buggy R code and rushed a preprint out the door without proofreading or sanity checking the numbers.

The main claim of the paper is this:

The total number of estimated laboratory–confirmed cases (i.e. cumulative cases) is 18913 (95% CrI: 16444–19705) while the actual numbers of reported laboratory–confirmed cases during our study period is 19559 as of February 11th, 2020. Moreover, we inferred the total number of COVID-19 infections (Figure S1). Our results indicate that the total number of infections (i.e. cumulative infections) is 1905

... (read more)

I was particularly bemused by quoting cumulative infections to 7 significant figures where the 95% confidence interval spanned a factor of 2. This did not fill me with confidence...

[ Question ]

Preprint says R0=~5 (!) / infection fatality ratio=~0.1%. Thoughts?

by Hauke Hillebrandt 1 min read20th Mar 202029 comments

6


What do people think of this preprint from March 13th?

It suggests:

  • 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?

[Reddit thread]

From paper:

"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"

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Like others I doubt the infection and fatailty rates because of South Korea and Diamond princess (if the author knew about how much this result conflicts with those datasets then its up to them to argue why the new paper is better).

R0=5 isn't completely unbelieveable. If the doubling time without containment measures is 2 days and the infective period is 12 days (i.e. 5 days incubation period and a week afterwards) then R0=5. Unfortunately based on the rather unbelievable infection and fatality rates I don't think this paper really adds any evidence for this - it suggests the model is fatally flawed.

New editorial about the asymptomatic rate in Nature - the author of the preprint above are featured in this as well. They say asymptomatic and mild case rate might be up to 50% of all infections and that these people are infectious.