
Italy extends lockdown amid hopes of turning corner - fspeech
https://www.bbc.com/news/world-europe-52100153
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carlob
I'm not an epidemiologist, but I have some background in Bayesian problems in
biophysics.

Some back of the envelope math for Lombardy, the hardest hit region:

Total population ~ 10M

Total deaths (2020/3/30) = 4773

If one assumes an Infection Fatality Rate of 1% then we would have had 500k
cases in the region about two weeks ago. Assuming a doubling of the cases
every 5 days, this means that the current actual number of infections stands
at 4M and it would take log2(10/4) = 1.3 new doublings to reach saturation:
about a week.

Taking instead an IFR of 2% and doubling every 7 weeks, we'd have about 3
weeks left to herd immunity.

Of course one should take into account the fact that at some point this will
stop behaving like an exponential and look more like a sigmoid, but herd
immunity doesn't need 100% infection, so the orders of magnitude involved
should be more or less the same.

This seems to be roughly consistent with what some more authoritative sources
are saying for example [0] claims Italy is probably missing 95% of cases.

[0]
[https://cmmid.github.io/topics/covid19/severity/global_cfr_e...](https://cmmid.github.io/topics/covid19/severity/global_cfr_estimates.html)

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bestouff
I think it's past time to introduce "IANAE".

