Anthony Fauci
Anthony FauciReuters

Top US infectious disease expert Dr. Anthony Fauci on Sunday said he was "dismayed" and "stunned" when former President Donald Trump was booed by his supporters when he told them during a speaking tour that he has received a COVID-19 vaccine booster shot.

"I was a bit dismayed when former President Trump came out and made that statement, and his followers booed him, which I was stunned by that. I mean, given the fact of how popular he is with that group, that they would boo him, which tells me how recalcitrant they are about being told what they should do," Fauci told ABC's "This Week with George Stephanopoulos".

Trump revealed last Sunday, during an appearance in Dallas with Bill O'Reilly, that he received a booster shot of the COVID-19 vaccine.

When the crowd reacted to Trump’s announcement with boos, the former President urged them not to do so.

Prior to the booing, Trump told the audience that they should "take credit" for the success of the vaccines developed while he was in office.

"Look, we did something that was historic. We saved tens of millions of lives worldwide. We together, all of us -- not me, we -- we got a vaccine done, three vaccines done, and tremendous therapeutics. Take credit for it. Take credit for it.... Don't let them take it away. Don't take it away from ourselves," he said.

"You're playing right into their hands when you sort of like, 'Oh the vaccine,"' he added. "If you don't want to take it, you shouldn't be forced to take it. No mandates. But take credit because we saved tens of millions of lives. Take credit. Don't let them take that away from you."

Fauci said in Sunday’s interview that he hopes Trump will continue to tell people to get vaccinated.

This past Thursday, White House press secretary Jen Psaki told reporters that the White House is “grateful” that Trump received a booster shot of a COVID-19 vaccine.

“We are grateful that the former President got the booster. We’re also grateful that he made clear in a recent interview that they’re effective and they’re safe. And that’s an important message for anyone to hear,” Psaki said.

"This is not a partisan issue. This is about saving lives, communicating accurate information, pushing back against inaccurate information, and in this particular case, the former president did that,” she added.

Two days earlier, as President Joe Biden announced his plan to fight the Omicron variant of COVID-19, he mentioned the crucial role the Trump administration played in getting the vaccines produced and distributed.

Trump later toldFox News he is "very appreciative" and "surprised" that Biden thanked him and his administration.

"I'm very appreciative of that — I was surprised to hear it. I think it was a terrific thing, and I think it makes a lot of people happy," said Trump.