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PLC
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Oct 3, 2020, 7 tweets

The countries of Southeast Asia have reported essentially zero Covid-related deaths with many theories posited regarding the source of this surprising "immunity", but newly shared mortality data from S. Korea may have solved this mystery.

The Human Mortality database, a collaboration of UC Berkeley and the Max Planck Institute in Germany have recently added South Korea weekly mortality data back to 2010 which supports the "dry tinder" or mortality displacement hypothesis:

After a long period of remarkable consistency, South Korea has had three straight bad "flu seasons", with 2018 being especially bad. Unlike Europe and the Americas, 2018 was not followed by mild years but by two more bad years:

In total, there have been 56K more deaths than expected during the past three years leading up to the Covid period. In other words, Korea has not reported any Covid fatalities because their potential susceptible population had already died:

Interestingly, the 2018 excess mortality in Korea equates to 577 deaths per million, almost perfectly equal to Italy's Covid deaths per million. The three year cumulative excess would place Korea #1 in the world for Covid deaths.

Could the entirety of the divergence between SE Asia and W. Europe come down to the severity of prior flu seasons and resultant mortality displacement? Could it be that track-and-trace, masks, travel bans, etc, had absolutely no impact on the course of this disease?

More provocatively, what was going on in Korea (and likely all of Southeast Asia) from 2018-2020? What explains three straight bad Winters when, generally, one bad Winter is followed by mild?

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