A leftover from yesterday. Not only do I believe them, I think maybe they’re being conservative about the timeline. Given the astounding drop in cases in California lately, we’re left to wonder if they haven’t achieved a degree of herd immunity already.

“If L.A. County receives 500,000 doses a week,” said [L.A. County Public Health Director Barbara] Ferrer on Wednesday, “80% vaccination of 16 and over can happen in just 12 more weeks.”…

Ferrer says that 30 to 40% of county residents have already been infected and so would have immunity. Fauci this week cited a study that asserted 45% of people in Los Angeles have Covid-19 antibodies. Assuming the majority of those people have not been vaccinated, one might then peg the number of immune L.A. residents under 16 with virus-exposed immunity at about 10% of the entire population.

Ferrer says that 80% of the remaining 16+ population should be vaccinated by late June — which comes out to 64% of overall residents. When one adds in the 10% of the under 16 population with virus-exposed immunity, it seems reasonable to say approximately 74% of all Los Angeles residents will have immunity by late June. That’s well within Fauci’s 70-85% requirement for herd immunity.

I have no deep thoughts on that but I do want to show you what the numbers look like statewide in California lately since they haven’t gotten as much attention as they deserve. Most of the focus is on the resurgence of COVID in Michigan and New York, which is partly due to the media’s “bad news bias” and partly due to pressure from the expert class to keep the public vigilant instead of letting down their guard. And the trend *is* worrisome: Cooler northern states are seeing rising cases, especially ones like Michigan where the British variant is prevalent.

But California? California is killing it.

The seven-day average in cases lately has been below 2,600 per day, the lowest the state has seen since last May. New York has half the population of California and saw more than three times as many cases yesterday. Michigan has one quarter as many people as California and saw 7,000+ cases. Fewer than 3,000 in a state of 40 million people is freakishly good.

Here’s what it looks like when measured by positivity rate. California is currently sitting at 1.5 percent. No typo.

Michigan’s positivity rate is 14.3 percent by comparison.

What’s going on Cali? No one has any silver-bullet explanation, just a stew of the obvious ones. First, the weather is warmer than in the northeast and there does seem to be a “seasonal” effect with the virus, which also explains Texas’s declining case counts. Second, vaccinations keep rolling along, with 31 percent of California’s population having received at least one dose. Third, as noted in the excerpt, a large share of the public may have already acquired immunity the old-fashioned way during California’s ferocious winter wave. Combine the people who are naturally immune with the people who have been vaccinated recently and suddenly the virus is running out of people to infect. Herd immunity’s setting in.

Except … two of those explanations also apply to New York. Cuomo’s state has also dished out first doses to 31 percent of its population. And of course New York suffered the most catastrophic wave of COVID of any state during the pandemic last spring. If anyone has a lot of native immunity in the population, we’d expect it to be New Yorkers. And yet, as I say, cases are rising in New York State right now. Why aren’t they faring as well as Californians are?

Two possibilities. Maybe the weather is a really big factor in COVID transmission or maybe California has been largely spared the sort of nasty variants that New York and Michigan are coping with. New York has its own homegrown strain and Michigan has an unusually high number of cases of the British strain. It could be that Cali simply lucked out by having neither of those variants take hold locally.

Except … California had its own homegrown strain too. We haven’t heard much about it lately but scientists were chattering about it a month ago. Is it possible that that variant was unusually contagious, if not unusually dangerous, and infected a disproportionately high number of locals this past winter, seeding a greater degree of herd immunity now?

Tiana Lowe has another theory:

Gavin Newsom is terrified of being recalled so he's reopening almost everything. This got COVIDiots out of California's notoriously congested, multigenerational housing and instead outside. It's political, but in a weirdly good way. https://t.co/v6bS403Q0G

— Tiana Lowe (@TianaTheFirst) April 1, 2021

Has the end of lockdowns solved California’s COVID problem by freeing people to go outside? The wrinkle in that theory is that cases have been falling for two months but a huge share of the population is still under restriction. Only now, with infections at rock bottom, are the remaining precautions beginning to lift. In fact, L.A. County, which has a quarter of the state’s population, isn’t lifting restrictions until next Monday. It could be that Californians have been out more lately as the weather’s improved despite what the rules say, not because of them.

Whatever the answer, even the experts are cautiously optimistic that the state’s going to avoid the sort of last-gasp wave that New York’s dealing with. Cases are too low, vaccinations are happening too quickly, and the weather’s too warm for the virus to regain meaningful momentum. That’s the theory at least. Fingers crossed.