Wednesday was a big day in the fight against the coronavirus. It’s the day the U.S. government launched its campaign to get Americans to take booster shots for the vaccines, amid the increasingly challenging situation brought on by the delta variant.

It’s also the day in which a Fox Business Network host tried hard to goad former president Donald Trump into questioning that effort — and succeeded.

Trump, who has on a few occasions urged vaccinations but has generally avoided lifting a finger to really convince skeptical Republicans, on Wednesday pitched the booster effort as essentially a money-grab by Big Pharma.

“That sounds to me like the moneymaking operation for Pfizer, okay?” Trump said. “Think of the money involved. … The whole thing is just crazy. It doesn’t — you wouldn’t think you would need a booster. You know, when these first came out, they were good for life.”

The first thing to note is that Trump is simply wrong that these vaccines were pitched as being “good for life.” The idea that boosters might eventually be needed has always been on the table, since back in the Trump administration, because of the nature of coronaviruses. If Trump didn’t know that, then he really wasn’t paying attention when these were being developed under his administration.

The second thing is that if there’s someone who might understand the need for boosters, it would seem to be Trump himself. After all, he was diagnosed with the coronavirus in October and still got the vaccine in January (though he didn’t tell people at the time). He did so despite having some natural immunity from his infection.

Perhaps the most remarkable aspect of this, though, is how much Trump was effectively drawn into this by Fox Business host Maria Bartiromo — after he spent a fair amount of time promoting the vaccines more generally.

As new coronavirus variants emerge and the longevity of vaccine protection remains unknown, scientists are researching how booster shots could work. (John Farrell/The Washington Post)

Bartiromo set up the interview by throwing a bunch of topics at Trump, including the boosters. When she asked, “Sir, would you get a booster shot?” Trump didn’t answer the question but did play up his administration’s efforts on the vaccines.

Bartiromo then asked Trump about breakthrough cases for those who have received the vaccines. Again, Trump used the occasion to promote the vaccines and — as he has on a few occasions — told people to get them.

It was actually one of Trump’s most forceful endorsements of the vaccine.

“I recommend that people take it,” he said. “I also recommend that you have your freedoms to do what you want to do.”

Trump added: “Now one thing: When you have the vaccine, people that do — and it’s a very small number relatively, but people that do get it — get better much quicker. And it’s very important to know. They don’t get nearly as sick, and they get better. [Sen.] Lindsey Graham is an example. He said, if I didn’t have this vaccine, I would have died.”

“So once you get the vaccine, you get better,” Trump added.

Pretty strong endorsement. But at this point Bartiromo began interrupting him and suggesting maybe there should be a “but” involved.

“It’s a great point,” she said, “but I still come back to the idea — I still come back to the idea of a booster shot. I mean, yes, you are right, the vaccines work — "

It’s at this point that Trump took Bartiromo’s cue and ran with it, pitching the booster shots for a vaccine he supports as some kind of money-grabbing conspiracy. This despite many vaccines having booster shots and more than a year of suggestions that this need would arrive one day.

Fox News and Fox Business have tempered some of the vaccine skepticism that has been a feature of their broadcasts for much of this year. But if there’s one segment that shows how old habits die hard and how irresistible it apparently is to feed into vaccine doubts — for both their pro-Trump hosts and Trump himself — it came almost immediately after the booster campaign began in earnest.