Bo, you're correct in urging a certain caution when it comes to interpreting the Oxford study. One issue is, as you mention, the limited geographic area. Interestingly, data released from the NHS in Wales a few days ago (e.g. a few weeks after the pre-print release of the Oxford study) showed that around 70% of covid-19 deaths were in people who were obese. Meanwhile there's accumulating data in several US States that also seem to indicate that obesity is indeed a higher risk factor than the Oxford study would suggest.