Former President Donald Trump found himself on the receiving end of his supporters’ disapproval this weekend after revealing that he had recently received a booster vaccination shot against COVID-19.

Trump’s booster announcement came during Sunday’s final stop on the “History Tour” he co-headlined with disgraced former Fox News star Bill O’Reilly. The tour, which Trump had promised would bring “big crowds,” has so far been beset by middling attendance and empty seats.

At one point during the event, as reported by Newsweek, Trump bragged that the COVID-19 vaccines were developed by his administration under Operation Warp Speed. Calling the effort “historic,” the ex-president took personal credit for saving “tens of millions of lives” around the world.

“We should take credit for it, and you play right into their hands [when you doubt it],” he also lectured the crowd.

Vaccine hesitancy among Trump supporters has had a real-life impact, as data shows that counties that voted heavily for Trump in 2020 “have been nearly three times as likely to die from COVID-19 as those who live in areas that went for now-President Biden” since May 2021. This is almost entirely attributed to those counties’ low vaccination rates.

While boasting about his administration’s role in vaccine development, Trump simultaneously expressed his opposition to vaccine mandates, drawing cheers from the MAGA attendees. “If you don’t want to take it, you shouldn’t be forced to take it, no mandates,” he declared.

The cheers, however, suddenly turned to boos and jeers when both he and O’Reilly confirmed they were fully vaccinated and boosted.

“Don’t, don’t, don’t,” Trump immediately reacted, pointing to one side of the arena where the groans apparently emanated.

“That’s alright, it’s a very tiny group up there,” the twice-impeached former president then insisted.

Trump’s affirmation that he has received a booster shot comes just a few months after he bashed the need to get an additional vaccination jab. During an August interview with pro-Trump Fox host Maria Bartiromo, Trump—who has constantly peddled mixed messages to Republicans on vaccines—was goaded into dismissing the booster campaign.

“That sounds to me like the moneymaking operation for Pfizer, okay?!” Trump bellowed. “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.”

And in a September interview with The Wall Street Journal, the 75-year-old ex-president suggested that he would not get a booster shot, saying “it’s probably not for me” and that he was “in good shape from that standpoint.”