Thread by @RuminatorDan

An estimated 750M, 10% of world’s population have been infected by Covid-19, says WHO's Dr M Ryan

This implies far lower Infection Fatality Rate than previously claimed & potentially significant implications for many countries.

Analysis:

[5Oct2020_1]

irishtimes.com/news/ireland/i…

While clearly this is only a "best guess" figure, we can still conduct a rough analysis, leading to an interesting conclusion.

10% of world population ~ 750M
Covid-19 deaths to date ~ 1M
Implied IFR = 1/750 = ~ 0.13%
(IFR = Infection Fatality Rate)

An IFR of ~0.13% is almost an order of magnitude lower than the ~1% values seen in much of the predictive modelling that has been used to guide policy, lockdown decisions etc. (E.g. ICL used 0.9% for UK in March).

Even for a rough estimate, this is a significant difference.

An order of magnitude reduction in IFR implies a similar reduction in predicted fatalities

For, e.g, UK & others, this means 10's rather than 100's of thousands of deaths.

ICL predicted several hundred thousand UK deaths in the "do nothing" scenario.

This did not happen.

UK total covid-19 fatalities to date are ~42k; indeed 10's & not 100's of thousands.

The same appears generally to be true for the higher fatality locations. Fatalities have been approximately an order of magnitude lower than predicted.

Responsible & fair to re-remind ourselves that the WHO surely meant this number as a rough estimate. However an order of magnitude difference is very large in this situation & adjusting that "10% infected" figure up or down somewhat would make little difference to the results.

Even more interesting is the potential implication of this for today & the future, especially for those locations that have already experience high fatalities (eg. UK)

Many in these locations believe that, unless strict measures are maintained, huge numbers of deaths will occur.

However, the WHO's own implied IFR & it's consequences would seem to support the hypothesis that, while further infections & deaths in these locations are possible (as with many viruses), in terms of the bigger picture the epidemic may well have largely run its course.

[Analysis, opinions and errors my own.]

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