I read months agp that the wesr coast had a milder version of Covid than what hit Italy and our east coast.
It is possible, but I heard this months ago as well and one would think that this would have been confirmed by now. I suspect that the difference has more to do with viral load on initial contact. People out west do not use mass transit nearly as much or live crammed in high rise apartments as often. When you are sharing a small space with an infected person your chances of getting more viral particles than your body can fight off are greater than if you pick your nose after using a shopping cart at the grocery store.