For months, journalists including yours truly have posed a question: What would GOP vaccine hesitancy look like if Donald Trump were more forceful in combating it? Trump, despite hailing the manufacturing of the vaccines during his administration, spent months conspicuously declining to actually tell people to get them — or to disclose that he himself got vaccinated. Trump eventually told people on a few occasions to get the shot. But polls show that most of the unvaccinated don’t know Trump has been inoculated and don’t believe he actually supports vaccination.

On Saturday night, we got a little taste of how difficult that vaccine-resistant genie will be to put back in the bottle. And it wasn’t the only evidence that Trump’s GOP will struggle to confront the conspiratorial impulses it has allowed to spread largely unchecked.

Speaking at a rally in Alabama, Trump offered one of his most forceful endorsements of vaccines to date.

“I believe totally in your freedoms. I do. You’ve got to do what you have to do,” Trump said, before adding with emphasis: “But, I recommend take the vaccines. It’s good. I did it. Take the vaccines.”

It was at this point that the crowd began to stir. Some didn’t like this message from the former president they had come to support. There were some jeers.

Trump again qualified his remarks by noting that this is about personal choice.

“You got — no, that’s okay. That’s all right. You got your freedoms. But I happened to take the vaccine,” Trump said, before defusing the situation a bit with a jokey comment: “If it doesn’t work, you’ll be the first to know.”

But then he added: “But it is working.”

It was a sight to behold: Trump being booed at a rally by his own supporters. A look at the archives suggests that’s largely unprecedented, save for when Trump praised Tom Brady at a 2016 rally in Maryland.

To be clear, this was a small portion of the contingent at the rally. It was also in Alabama, which is one of the most vaccine-resistant states in the country (current vaccination rate ranking: 50th out of 50 states). We often oversell the importance of the loud and passionate few in these settings. But this was still Trump getting heckled by his own supporters, which hasn’t really happened for a reason. Trump’s base has generally been all about the man, and less about the policies and details. But here, they didn’t like the actual details.

It was also merely the latest evidence that the monster that has been created, however much culpability there is for Trump personally, won’t go away quietly.

Earlier last week, Trump also promoted the vaccines during an appearance on Fox Business Network. Asked to respond to the Biden administration’s announcement that booster shots are now recommended, Trump launched into another relatively strong endorsement of the vaccines.

But as he was doing so, Fox Business Network host Maria Bartiromo cut him off and pressed him to weigh in specifically on the boosters. She set up the question skeptically. “But … I still come back to the idea of a booster shot. I mean, yes, you are right, the vaccines work —” Bartiromo said.

Trump took her cue and ran with it, suggesting that perhaps the boosters were a money grab by Big Pharma.

Even in the same rally Saturday night in Alabama, a similar situation played out on a different topic: the 2020 election results. Rep. Mo Brooks (R-Ala.) had the temerity to urge supporters to focus on future elections.

“There are some people who are despondent about the voter fraud and election theft in 2020,” Brooks said. “Folks, put that behind you. Put that behind you.”

Again, the crowd began stirring. But Brooks doubled down.

“Yes. Look forward. Look forward. Look forward,” Brooks said as the crowd declined to yield and boos continued to ring out. “Beat them in 2022. Beat them in 2024.”

Ultimately, Brooks was chastened, and he backed off.

“All right, well, look back at it, but go forward and take advantage of it,” he said. But the crowd was still unhappy.

Again, the caveats about noisy protesters apply here. But Brooks was also arguably Congress’s biggest promoter of the “big lie” that the election was stolen. Not even he has apparently banked enough goodwill among this type of crowd to be able to say this relatively anodyne thing about focusing on future elections. (Brooks is running for Senate in 2022, with Trump’s support.)

The election-fraud situation is a more clear-cut case of the likes of Trump and Brooks creating a monster that, at least on this night, turned on Brooks. If you feed people these kinds of lies on a topic of such import and they come to internalize them, it shouldn’t really be surprising that they will buck when you suggest it’s time to move on.

The vaccine situation is more nuanced, in that it’s less about Trump personally and proactively seeding vaccine skepticism. It’s more about him fading into the background as some of his most influential allies, particularly on Fox News, picked up that mantle. But that was still a choice. Every other living president has appeared in ads promoting the vaccines.

There’s a bit of a cause-and-effect question here. Would Trump’s early and more authoritative endorsement of the vaccines have made that much of a difference? A recent poll showed that just 5 percent of Republicans who said they did not intend to get vaccinated would change their mind if Trump urged them to do so.

But that finding isn’t hugely enlightening, in that it requires people to essentially admit they are taking their cues from someone else (rather than reaching this decision on their own). That’s not an attractive option. Another poll in March asked this question in a better way, disclosing Trump’s earliest endorsement of the vaccine to some respondents but not to others. While 43 percent of Republicans who weren’t told of Trump’s endorsement said they would get vaccinated, that number rose to 57 percent for those who were informed of it.

Trump never could have purged his party of all of its vaccine skepticism, but there is plenty of evidence he could have made a significant difference — if for no other reason than it might have sent a cue to some allies who have filled the vacuum by pushing dubious claims about vaccines.

But regardless of how we get here, the situation is the same: Getting those people on board with vaccinations is now much more difficult, because they have staked out their position — just as it will be very difficult to get people off the election falsehoods now that they’ve been told ad nauseam. If your allies are telling people their democracy has been stolen from them or that an injection might be dangerous or unnecessary, it takes effort to combat that and counteract it.

That effort has been almost wholly absent from members of Trump’s party. They have pretended they cannot do much besides give their own thumbs-up to the vaccine, even as colleagues like Sen. Ron Johnson (R-Wis.) spew misinformation. They’ve pointed to their own more-circumspect comments about supposed election irregularities, while doing almost nothing to address or combat claims by Trump and his allies that go significantly further.

They are clearly terrified of saying anything that would create a rift in their party. They want to win elections and don’t need dissension. But Saturday night demonstrated how difficult it will be to combat the conspiracy theories that have infected the Republican Party’s base — particularly if Trump, who minds his base relentlessly, responds to the rebuke by backing away from vaccines.

These conspiracy theories need to be inoculated against early on, before the virus can take hold. But sometimes the will to do that, it seems, just isn’t there.