I'd say the pre-vax differences likely came from how people treated public health advice and precautions. If somebody believed it was no worse than the flu or e

I'd say the pre-vax differences likely came from how people treated public health advice and precautions. If somebody believed it was no worse than the flu or even didn't exist (like some of my in-laws in Summer 2020), they would be far more likely to catch it, spread it, and receive poor treatment. Those differences in behavior would carry over to vaccination rates, since that's also responding to public health recommendations. It's hard to believe Silver didn't do the analysis on pre-vax death rates, but he didn't mention it so I don't know. If COPD and similar conditions were the major difference, I would expect the difference in death rates to be closer to 2.3x (13.6%/5.9%) than 2.9x (73/25 per 100k). Those are very different ratios. And I don't know about any other complicating conditions with larger relative rates than 2.3x for those two states. Obesity is only 1.3x higher in West Virginia. So this gets back to Silver's point: you can almost always find other contributors, but that doesn't necessarily prove something else didn't contribute. You have to do that analysis all together. But complicating health conditions don't seem to be able to account for the differences, even before a regression test.