To be clear, this is a individual strategy not a group one. It's moving from a place with a curve that spikes late, to a place with a curve that spikes early, such that you dodge both spikes. This doesn't work for society as a whole (which can't just up and move to dodge the virus).

Nor am I claiming that California has yet achieved any substantial degree of herd immunity. Just that projecting current rates forward I think you will before I actually end up moving there (it helps that I have a lot of flexibility).

That said, the 70% figure in your article is too high. Research [1] and experience in Sweden [2] suggests that there are substantial benefits at just 40%.

[1] https://science.sciencemag.org/content/early/2020/06/22/scie...

[2] https://translate.google.com/translate?sl=sv&tl=en&u=https%3...