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I have seen multiple sources claiming that the fatality rate of the 2019-nCoV virus is around 2% to 10%.

At the same time, as of February 3rd 2020, 362 patients were reported to have died from the virus, while only 523 have recovered. [1]

Simple maths show that this would result in a fatality rate of 40.9%.

So where is this great difference in values coming from?

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  • 3
    Better question for a site like Biology.SE
    – rjzii
    Feb 3, 2020 at 13:24
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    There is a very similar question on MedicalSciences: medicalsciences.stackexchange.com/questions/20970/… It's fine there IMO, but I would not recommend posting it to Biology.
    – Bryan Krause
    Feb 3, 2020 at 23:47
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    A simple assumption that all who've contracted the illness have been put in either the 362 and 523 numbers. It's a false assumption. Only the very ill are counted in those numbers; only the ones shown up at the hospital.
    – user11643
    Mar 12, 2020 at 20:06
  • Simply put, "died" and "recovered" aren't the only possible states for those infected; you've neglected to include "currently alive and infected", which covers far more people (currently) than the other two categories.
    – anaximander
    Mar 16, 2020 at 15:57

1 Answer 1

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Take a look at this live map of the virus. The calculation is based on the number of deaths, divided by the number of confirmed cases (multiplied by 100 to get it as a percent%).

As of February 3rd 2020, that would be 362 / 17405 * 100 ~= 2.08% fatality rate.

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    If that's true, the fatality rate is a really bad measurement for how dangerous a disease is. If a disease (like 2019-nCov) takes longer to show symptoms (and possibly kill you) the fatality rate would be low because many more get infected before deaths occur, allthough the fatality chance can be almost 50%. Correct?
    – Markus Appel
    Feb 3, 2020 at 10:03
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    @MarkusAppel The issue is that the 2019-nCoV has only been out for about a month, so the number of people who are either dead or who recovered from the virus are much lower than for the number of ongoing cases. The fatality rate is going to undergo pretty drastic changes until things settle down. With time, the number of ongoing cases is outshined by the combined number of deaths + recovered cases. For short: yes, it's a mediocre way to measure fatalities early on, but it becomes more accurate in the long term.
    – Asmael
    Feb 3, 2020 at 10:40
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    There is also the problem with underreporting. Mild cases might get diagnosed as a regular seasonal flu or not get diagnosed at all.
    – Philipp
    Feb 3, 2020 at 13:08
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    FWIW: it seems that people who are going to die, do so in the first 5-7 days, even though recovery takes longer [citation-needed desperately]
    – Oddthinking ♦
    Mar 11, 2020 at 7:17
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    @Oddthinking "From illness onset, the median time to discharge was 22 days, and the average time to death was 18.5 days." eurekalert.org/pub_releases/2020-03/tl-pss030920.php
    – DavePhD
    Mar 11, 2020 at 14:30

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