We had the same strange phenomena here in Washington State where the first was actually diagnosed in January after returning from China. We have half a million recent Chinese residents, legal and illegal living in Eastern King County and Eastern Snohomish County. A lot of them visited home for Chinese New Year.
I was poo pooed earlier this year when I said that people in our area probably were already close to herd immunity if it really was as contageous as thought.
I read months agp that the wesr coast had a milder version of Covid than what hit Italy and our east coast.