AC from Finland is right ... CA didn't do things nearly as well as they could/should have been done. We had very, very delayed and inadequate testing. We did lock down relatively early, and are reopening more slowly than some states, but a good deal of people didn't (and still don't) take the mask orders or stay at home orders seriously.

You'll also notice a huge difference between Northern and Southern CA, in terms of cases. Northern CA has been more compliant about obeying ordinances, which has helped. It's still far from perfect, but I do think the difference in behavior is pretty pronounced in terms of spread.

I've been mulling over the prion aspect of things, too. We know that research on prion diseases goes way back, and that some of them have been studied as weaponized agents over the years. (If you want to go down a rabbit hole, look into the theory that the cow mutilation phenomenon in the US was actually a secret operation to test for prion diseases, following their use in field tests during the Cold War. )

Some prion diseases were originally thought to be viruses, they spread so easily (for example, Scrapie and Wasting Diseases in deer) -- whereas other seem harder to spread, though coming into contact with infected tissue through the food chain will certainly do it. They were also once thought to be species specific, though not all of them are.

Really, this is the scenario that makes the most sense, if China really is afraid of the meat supply being contaminated.... and it's a very frightening thought. I'm going to continue to mull this over.