California shut down very hard and fast. When they reopened, nearly 100% of the population was still susceptible to the virus, so it spread like wildfire. Especially since the reopening was not exactly slow.
Compare this to the Northeast and much of Western Europe where the virus spread too quickly until lockdowns reduced the spread. Now, keeping the transmission rate low in those areas has become comparatively easy, even with wide-scale reopening.
Perhaps California could have attempted a middle ground strategy. Let the virus spread just a slight amount more than occurred during the initial lockdown in order to gradually spread immunity. The level of immunity may be nowhere near "herd immunity", but any amount of immunity in a population makes transmission of the virus more difficult.
EDIT: Part of why I make this strange argument is because CA seems to have endured a lockdown for virtually no gains. Now, the lockdowns will begin again. Perhaps allowing the virus to spread at a low and manageable rate would have conferred some benefits in terms of increased immunity in the population, thus making it easier to suppress the transmission rate moving forward.
Compare this to the Northeast and much of Western Europe where the virus spread too quickly until lockdowns reduced the spread. Now, keeping the transmission rate low in those areas has become comparatively easy, even with wide-scale reopening.
Perhaps California could have attempted a middle ground strategy. Let the virus spread just a slight amount more than occurred during the initial lockdown in order to gradually spread immunity. The level of immunity may be nowhere near "herd immunity", but any amount of immunity in a population makes transmission of the virus more difficult.
EDIT: Part of why I make this strange argument is because CA seems to have endured a lockdown for virtually no gains. Now, the lockdowns will begin again. Perhaps allowing the virus to spread at a low and manageable rate would have conferred some benefits in terms of increased immunity in the population, thus making it easier to suppress the transmission rate moving forward.