A few sage words from former president Donald Trump, encouraging his Republican supporters to get the COVID jab, could be a “game-changer” in America’s coronavirus response, Dr Anthony Fauci has said.

His comments came after a poll revealed about half of US men who identified themselves as Republicans said they had no plans to get the vaccine.

The US government’s top infectious disease expert hopes Mr Trump would use his popularity to persuade his followers to get vaccinated against COVID-19, saying “I think it would make all the difference in the world” given he still has “incredible influence” among Republicans.

“If he came out and said, ‘Go and get vaccinated. It’s really important for your health, the health of your family and the health of the country,’ it seems absolutely inevitable that the vast majority of people who are his close followers would listen to him,” Dr Fauci told Fox News on Monday morning (Australian time).

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It would be a “game-changer” for the country’s vaccine efforts, he said, calling the shots a “commonsense, no-brainer” public health measure.

In late February, while at a conservative political gathering in Florida, Mr Trump urged people to get vaccinated, saying, “everybody, go get your shot”.

It was the first – and only time – he had encouraged people to do so.

Mr Trump hasn’t been among former presidents and public officials who have been vaccinated on camera to encourage others to get the shot.

It was revealed only recently that he was vaccinated in private at the White House before leaving office in January.

Dr Anthony Fauci, advisor to President Joe Biden, wishes Donald Trump would encourage his supporters to get the jab. Photo: AAP

Mr Trump also did not appear in a new US public service campaign for the COVID-19 vaccine that included former presidents Jimmy Carter, Bill Clinton, George W Bush and Barack Obama.

Polls have shown Republicans joining black Americans and other groups in expressing greater skepticism than others about the safety of the vaccines.

Dr Fauci said he doesn’t understand the resistance.

“What is the problem here? This is a vaccine that is going to be lifesaving for millions of people,” he said on NBC’s Meet the Press.

“I just can’t comprehend what the reason for that is when you have a vaccine that’s 94-95 per cent effective and it is very safe. I just don’t get it.”

The number of vaccine doses distributed and administered each day in the US is rising, with more than 2.5 million daily shots in arms on average in the last week.

About one in five Americans have received at least one dose, with about one in nine fully vaccinated, according to the Centres for Disease Control and Prevention.

Coronavirus deaths and newly confirmed infections have tumbled over the past two months in the US. But cases are running at a still-troubling average of about 55,000 a day.

Dr Fauci repeatedly warned against pulling back on public health measures too early, saying the virus could come surging back, endangering the goal of getting the country closer to normal by early July.

He pointed to Europe as a cautionary tale, with rising virus cases coming after restrictions on the continent were rolled back.

-with AAP