In a previous thread, I explained that for a contamination curve displayed in log scales, the curve becomes a straight line which slope is directly linked to R0, the number of persons one infects. This are the curves for several countries, aligned by the time of 100th infections:
Japan clearly has always had a much lower R0 than anyone else. Studying their containement strategy is interesting. Here: https://medium.com/@shotamiz/how-japan-is-combating-sars-cov-2-covid-19-83b7dd8d3f9
and here as a twitter thread:
The simplest explanation of Japan’s infection spread rate bring so different could lie in
1. inaccurate reporting so as not frighten the World to stop the Olympics!
2. Too few tests
done due to government incompetence as shown previously in the Fukushima disaster
3. Unlikely but plausible: Some difference might be with perhaps less efficient virus binding to receptor sites in the respiratory epithelium or some other such factor essential to Virus replication.
So one line of inquiry for this speculation, would be to list all the known ways that a good chunk of the Japanese population differ in antigens, common enzyme deficiencies, gene duplication, epigenetic modeifications, other illness susceptibility differences, histocompatibility markers and the like.
Remember certain Javanese divers can stay under water longer simply because genetic adaptive variance in their hemoglobin’s capacity to bind oxygen.
Athletes trained in high altitudes can similarly more efficiently transport fresh oxygen, but the adaption is temporary, due to simply making more if the hemoglobin and essentially self-doping.
So one can see how simple genetic biological difference can drastically alter our endurance.