. In the US the variation in death rate is between different States and (within States) counties. It tracks vaccination and masking rates (as well as various medical care proxies such as childbirth mortality, political Party allegiance, education, income, and of course race). The US is undercounting Covid death rates by something on the order of 20%, depending mostly on State, btw - a factor to consider when comparing different countries: what are their criteria for a Covid death, and how reliable are their stats? ("Science" magazine has research reports addressing those factors, in June and July issues particularly).