Sorry, but that's a letter, not anything from which conclusions could be drawn. It's not any kind of study, contains no data, and is simply an assertion that it's risk compensation not variant strains that is causing waves. Absolutely nothing in that letter is actually offered to support that assertion. It's also very weak gruel, making it clear that Pelzman WAS arguing the very version of risk compensation theory that you have tried so hard to get us to discount-- the letter says Pelzman was claiming "that highway safety regulations were not reducing highway deaths".

It's an " internal " peer review, btw, and since there's no actual study, all that means is that it was reviewed to determine whether it contains anything in it that's provably false.

Ultimately, though, it has no useful implications. If you're vaccinated, odds are excellent that getting COVID is a relatively insignificant event requiring no hospitalization, so what we're seeing among vaccinated people is an increase in breakthrough infections, but not much increase in the rate of hospitalization or death. That isn't the case for the unvaccinated who get significant increases in all three in a wave. All the authors are doing is attributing the mask-resistant behavior of unvaccinated people to risk compensation from the vaccine. That seems perverse--it'd be like attributing crashes caused by people who don't wear seat belts to risk compensation of seat belts.