CFR, IFR, CMR & one more R:
Reality check.

I was deeply disturbed yesterday to hear a friend of mine claiming that the mortality from C19 is 5%.
Well, it is NOT!
Let me show you... 1/n

There are 3 ways to calculate mortality from a disease.
Each gives us a different set of information.
1.CFR- The Case Fatality Rate
2.IFR - The Infection Fatality Rate
3.CMR- The Crude Mortality Rate
2/n

1. CFR tells us how many people died out of the diagnosed cases with a (+) PCR test. There are so many infections hiding below the surface, CFR is a highly exaggerated mortality rate. It tends to decrease over time as the disease progresses and more cases are counted in. 3/n

2. IFR tells us how many people died out of the total infected. We can’t possibly know the total number of infections because not all infections reach the hospital so serological studies can give us a rough estimate by determining the number of people.. 4/n

who developed immunity to C19 as measured by C19 antibodies.

In reality, IFR stands to be lower because seroprevalence data does not capture all the infections in the population. IFR will be lower if we factor in T cell immunity and other levels of immunity. 5/n

Levels of immunity:

a) 1st Line of Defense: immune barriers (attacks any foreign body)

b) 2nd Line of Defense: phagocytes (White blood cells that gobble up any foreign body)

c) 3rd Line of Defense: T cells (targeting C19) produce antibodies that also target C19.

6/n

C19 can be attacked and eliminated at any level.

If it is attacked at the 1st or 2nd line of defense, this immunity will not be captured neither through an antibody test nor through a T cell test. 7/n

Now, do you think the WHO was fair when they compared the initial CFR of C19 with the IFR of the flu, when several orders of magnitude keep these estimates apart? 8/n

3. CMR tells us how many people died out of the total population. It is usually used to compare between countries, and is greatly affected by the population health status and healthcare capacity & quality (even if testing capacity & definition of deaths is the same) 9/n

The best indicators to gauge the lethality of a disease is the IFR (although still overestimated).

It’s extremely important to know that there is a huge disparity in the IFR based on the age group.
10/n

Children are completely spared and the elderly (above 70) are at serious risk from C19- as they are from any other disease.

Here are some samples showing IFR across the life span.
11/n

https://www.folkhalsomyndigheten.se/contentassets/53c0dc391be54f5d959ead9131edb771/infection-fatality-rate-covid-19-stockholm-technical-report.pdf

These are just rough estimates. Different studies provide us with different estimates.
12/n

https://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099(20)30584-3.pdf

@carlheneghan
« Taking account of historical experience, trends in the data, increased number of infections in the population at largest, and potential impact of misclassification of deaths gives a presumed estimate for the COVID-19 IFR somewhere between 0.1% and 0.41%.* »
13/n

This is between 1 to 4 deaths per 1000 infections for the general population. March 17, 2020

14/n https://www.cebm.net/covid-19/global-covid-19-case-fatality-rates/

Dr Ioannidis pinned the IFR at 0.26% in an aggregated estimate from 23 studies. June 8, 2020
15/n
https://www.medrxiv.org/content/10.1101/2020.05.13.20101253v2.full.pdf

The elderly are our most vulnerable.

To protect them, the young & healthy who are not at serious danger from C19, must find the courage to act like human shields. They can afford to get the disease to develop herd immunity and breakdown the chain of transmission for good.
16/n

Who is ready to be an immunity soldier to protect our most vulnerable?

#BackToLife

17/17

Check out my thread on CFR/ IFR - the general public needs to understand the iceberg of Covid 19.
@CllrBSilvester
@simondolan
@BreesAnna
@FatEmperor
@allisonpearson
@freddiesayers
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@RuminatorDan
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Look at how the CFR declines over the course of the epidemic. As more cases are counted, the denominator gets bigger and the % of deaths out of cases gets smaller.

https://www.cebm.net/covid-19/declining-covid-19-case-fatality-rates-across-all-ages-analysis-of-german-data/