There is no evidence that Sweden is anywhere near peaking. Quite the opposite infact.

The rule of thumb is deaths lag hospitalizations, hospitalizations lag cases. Bearing that in mind, Arizona's severe infecteds ratio actually looks slightly worse now than in did in summer.

As for New England, it's far too early to jump to conclusions. There needs to be time to see if there is the response in the lagging metrics. I suspect there will be that response, but even if there isn't it could be put down to the cases being in predominantly younger people (schools), mask wearing reducing the viral load or improved knowledge on how to treat. All these things would mean less severe infecteds and they are nothing to do with pre-existing immunity in the population.