Donald Trump revealed that he has taken his COVID-19 vaccine booster shot, prompting some of his supporters to boo him during a live event.

The former US president said he had taken his third vaccine dose while being interviewed live by former Fox News host Bill O’Reilly on Sunday in Dallas.

Video of the event that circulated on Monday showed that Trump’s confirmation was met with dismay by some audience members.

“Don’t, don’t, don’t,” Trump reacted as he waved down the jeers. “It’s a very tiny group [of people booing].”

Trump confirmed that he received his booster shot after making a defence of vaccines – and of his presidency’s role in getting them developed in record time.

“We got a vaccine done in less than nine months... it was supposed to take between five to 12 years. Because of that vaccine... I think this would have been the Spanish Flu of 1917 where up to 100 million people died.

"This was going to ravage the country far beyond what we’re seeing right now. Take credit for it,” he told his Republican audience. 

"What we have done is historic. You're playing right into their hands when you're all 'oh, the vaccine'.... we saved tens of millions of lives."

According to the New York Times, just 60 per cent of registered Republicans are vaccinated, compared to 91 per cent of Democrats.

Trump has previously said that he believes vaccines work and that people should take them, though he has argued against vaccination mandates and kept a low profile on the subject, which is a sore topic for many of his supporters.

Back in September, Trump had told the Wall Street Journal that he “probably” would not take the booster shot.