I cannot explain this map, but the clear division in compelling. A few lines divide the world into high, medium and low covid death rate countries and there are few exceptions in the high and low death rate areas.

All I have done is drawn some lines to a map from Our World in Data – eight straight lines and one with a single curve.

As I said, I cannot explain it, but I can rule out some things.

Its not government policies that are critical. Our World in Data has multiple maps of government responses, and there seems to be no sign of correlation.

Its not GDP either.

My first though was of a link with GDP, but while most of the worst affected countries are rich ones, there are two many execpetions both ways.

I cannot see any obvious link to how healthy populations are either.

It occurs to me that Japan, by far the biggest (in terms of population) first world country with a low Covid death rate has an unusually healthy population: in particular a healthy diet and very low rates of obesity. Maybe some combination of wealth and health is the explanation.