Foresight and hindsight

 By the late spring of 2021, there was a strong correlation between state-level vote for Joe Biden and Covid vaccination rates.  As a result, "blue" states had lower rates of Covid.  That continued to be the case during the summer and early fall, but at the end of November, Bret Stephens said that the relationship was breaking down.  The correlation between Biden support and Covid hospitalization rates was .25 at the end of November, down from .51 in late October and .63 in late September.  You could say that state-level Covid rates varied a lot from month to month, so that there was no evidence of change in the relationship (my interpretation), but on the other hand you could say that the correlation was getting weaker, which seemed to be what Stephens meant: "disease trends have a way of switching directions for reasons none of us really understands."  What do things look like now?  The correlation between Covid hospitalization rates as of a few days ago and Biden's share of the voter is about .30, about the same as it was in late November.  However, on closer examination things are a bit different.  The current relationship:

The District of Columbia is an outlier--if you exclude it the correlation is about .55.  At the end of November, it had moderate hospitalization rates, and didn't stand out--the correlation was about the same regardless of whether it was included.  

Of course, voting for Biden doesn't provide protection against Covid--what matters is getting vaccinated.  The correlation between state-level vaccination rates and Covid hospitalization rates:

March  7         -.37

late August     -.59

late Sept         -.75

late Oct          -.48

late Nov          -.15

early Feb         -.58

 It looks like late November was an outlier, maybe because that was in the early stages of the spread of the Omicron variant, so it was clustered in a few places.  At the time, Stephens said "Let’s put away our crystal balls and shake up our snow globes instead. We have about as much foresight in this crisis as a snowman in a blizzard."  But if someone had simply gone from vaccination rates at that time, they could have predicted current hospitalization rates pretty well.  That's because the pattern of vaccination rates hasn't changed much--they've gone up, but by about the same amount in all states (the correlation between state vaccination rates on Nov 30 and Feb 4, 2022 is 0.95).  In fact, if someone had simply gone from vaccination rates in late August, they could have predicted current hospitalization rates pretty well (a correlation of -.53).