There’s a lot on this topic floating around on news sites today. It’s been on my mind too every time we’ve heard some exciting new vaccination stat touted by the White House. (Eight million doses dished out last Friday and Saturday alone!) Right now the vaccine practically administers itself because we haven’t yet exhausted the population of people who are eager to get it. They’re motivated, they’re scheduling, they’re showing up, and the shots are going out.

Eventually we will exhaust that population, though. That’s when we hit “the wall,” the group of people who are persuadable but will take some convincing on the merits. And behind that wall is another wall, the group that’s distrustful of authority for whatever reason but can probably be brought around with the right message.

And behind that wall is the last wall, the anti-vaxxers, who aren’t getting their shots even if we pay them.

Which brings us to a momentous question. How soon relative to the threshold we need for herd immunity will we hit the first wall and see daily vaccinations slow down? Scientists guesstimate that we need 80 percent or so of the population immunized for herd immunity, which means 90 percent or more of adults. (At least until the vaccine’s available to kids, which it will be to middle-schoolers and older in a month or so.) If we peter out at 80 percent of adults getting vaccinated, maybe we can coast the rest of the way on natural immunity among unvaccinated people who’ve already had COVID. If we peter out at 70 percent, that’s a lot more coasting we’ll somehow have to do.

If we peter out at 60 percent, hoo boy.

Via Axios, this analysis suggests that we could hit the first wall in … three weeks. With less than 60 percent of adults immunized.

Big caveat there: What people say in surveys is a moving target. Before the vaccines arrived, polls showed far higher reluctance to get vaccinated; once the process began and fencesitters saw with their own eyes that there were no serious side effects for those who took the plunge, they began moving into the pro-vax column. (This same study shows that in December just 40 percent were already vaccinated or were enthusiastic to get the shot. By March it was 62 percent.) It’s possible if not likely that the persuadables who constitute the first “wall” will topple over easily as vaccination numbers continue to skyrocket and businesses begin opening up, incentivizing them to want to move about safely this summer. If it really does take us three whole months to go from 59 percent of adults being vaccinated to 67 percent, even with an economic and social boom happening across the country, that would be … bad. Really bad.

Which groups are most likely to find behind the various “walls”? Well…

Groups most likely to have gotten the vaccine in March, from @EchelonInsights polling

65+ 80%
Grad Degree 55%
Non-Trump GOP 46%
>$125k 46%
White 44%
AAPI 42%

Some of those least likely:

Trump GOP 34%
Black 24%
HS or Less 22%
Hispanic 18%

— Patrick Ruffini (@PatrickRuffini) April 9, 2021

MAGA Republicans and African-Americans continue to be overrepresented among holdouts. Based on that, you might expect states that contain large populations of both groups would have lower vaccination rates than the national average — and you would be right. Scroll through the NYT’s vaccine tracker and you’ll find that, as measured by the share of the population that’s received its first dose, all but six of the top 25 states went for Biden last November and all but seven of the bottom 26, if we include D.C., went for Trump. And two of those seven were Arizona and Georgia, which were practically ties. “[T]ake a look at the states that rank at the bottom in the nation in terms of percentage of the population that has received one shot: Mississippi, Alabama, Georgia, Tennessee, Louisiana, Indiana, Idaho, Wyoming, Missouri, Arkansas, and Texas,” writes Jim Geraghty. “What are those states full of? White Republican men and African Americans.”

If you’d prefer to measure vaccine uptake by the percentage of doses each state has used instead of the percentage of the population that’s received its first dose, click and look at Axios’s map. Once again we find poorer numbers among red southern states and stronger numbers among blue coastal ones. Geraghty has theories for why Republican men and African-Americans would be slower to get vaccinated than the average citizen is. Each group is suspicious of authority for different reasons, he notes, and blacks may be more reluctant because they see doctors at a lower rate than whites do and therefore are less likely to have a physician whom they trust to persuade them to take it. Blacks are also less likely to own computers than whites are, making scheduling a vaccine appointment more of a hurdle early on. But there may be more to vaccine hesitancy in the south than just the larger share of reluctant demographics:

The biggest obstacles to greater vaccine acceptance, he said, are the misinformation that flourishes on social media and the mixed messaging from Republican governors that leave people confused.

“By relaxing Covid restrictions, elected leaders in states like Florida, Mississippi, Texas and Georgia are pushing narratives about coronavirus that are working against a narrative that promotes the urgency of vaccinations,” he said. “And unfortunately, our vaccine campaigns are being undone late at night by Facebook and Twitter and Instagram.”

I’m not sure what Republican governors are supposed to do about that. Should they … not relax restrictions when it’s warranted because that might breed a false sense of security in vaccine resisters about not needing to get their shots to function normally? “We need to keep lockdowns in place to encourage immunization” is a sub-optimal policy program, let us say.

I’ll give you one more data point, this from the new KFF poll. Note that this is a survey of rural Americans specifically, not all Americans. And in rural America, blacks are *more* likely to want to get vaccinated than the average joe is.

The two biggest “definitely not” rural groups are … white evangelicals and Republicans. And Republicans are the only group in which the combined share of those who are already vaccinated or planning to get their shots ASAP is smaller than the combined share of those who definitely won’t do it or will do so only if required (which they won’t be). It’s totally possible that we’ll have a two-track pandemic in the U.S. by fall in which bluer states have reached herd immunity or are approaching it while red states continue to experience smallish outbreaks because they’re lagging behind.