We're underestimating how deeply cultural attitudes shape how many people get sick from Covid.

If you map the incidence of Covid in each Belgian county, for example, the border between French-speaking and Flemish-speaking parts of Belgium is startlingly obvious.

Another startling example:

Germany and the German-speaking parts of Switzerland have very similar rates.

France and the French-speaking parts of Switzerland also have very similar rates.

German-speaking and French-speaking parts of Switzerland have very different rates.

One more observation:

A lot of people who are very comfortable with cultural explanations in some contexts balk at them in others.

Do you believe that red-state America is worse affected because of a refusal to wear masks? Well, surely that, too, is a kind of cultural attitude?