# Is the death rate for Coronavirus between 3.85% and 3.9%?

The mortality rate (or case fatality rate, CFR) is currently defined as:
cumulative current total deaths / current confirmed cases. See:
3.4% Mortality Rate estimate by the WHO as of March 3

Using the 4 March figures for China the CFR would be 3012/80409= 3.746%.

The case fatality rate (CFR) represents the proportion of cases who eventually die from a disease.

Once an epidemic has ended, it is calculated with the formula: deaths / cases.

However while an epidemic is ongoing, current deaths belong to a total case figure of the past, not to the current case figure in which the outcome (recovery or death) of a proportion (the most recent cases) hasn’t yet been determined.

The correct formula, therefore, would appear to be:

CFR = deaths at day.x / cases at day.x-{T}
(where T = average time period from case confirmation to death).

One issue can be that of determining whether there is enough data to estimate T with any precision, but it is certainly not T = 0 (what is implicitly used when applying the formula current deaths / current cases to determine CFR during an ongoing outbreak).

A conservative estimate is T = 7 days as the average period from case confirmation to death. See:
https://www.worldometers.info/coronavirus/coronavirus-death-rate/

We have seen for T=0, using the 4 March figures for China the CFR would be 3012/80409 = 3.746%.

Using T=7, the CFR for China on 4 March becomes 3012/78824 = 3.837%.

Let’s look at how likely the CFR in China will actually be between 3.85 and 3.9%
(once there are no new cases).

We modify the colours in a table I created for a previous post to answer this question:
(Green shows CFRs within this range)

It looks like the death rate is likely to be be closer to 4%.

For background information, please see my previous posts:
https://aaamazingphoenix.wordpress.com/tag/coronavirus/

The next week or so may be sufficient to determine the CFR more precisely.

We note that there are still almost 6000 (5952) critical/serious cases in China, down from  6418 and just over 6800 in the previous two days. Scroll down to see the table at:
https://www.worldometers.info/coronavirus/

These may or may not affect the CFR dramatically. They have not done this to date.

Let’s hope the mortality rate (CFR) will not end up 4% or more.

Alan Grace
6 March 2020

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