A trio of former Presidents, Democrats Barack Obama and Bill Clinton, and Republican George W. Bush, announced on Thursday that they would publicly get vaccinated to demonstrate its safety to the 42 per cent of Americans who refuse to be injected with it, according to the latest Gallup poll.

The nation's top Covid-19 expert, Antony Fauci, whose statements on the pandemic have become the gold standard for scientific veracity, has also said he would let himself be injected with one of the vaccines that are hurtling towards approval.

"I may end up taking it on TV or having it filmed, just so that people know that I trust this science, and what I don't trust is getting Covid," Obama said during a satellite radio programme.

Staff of Bush and Clinton told CNN that the former Presidents would be ready to take the vaccine, which is expected to roll out in less than two weeks and be distributed to various categories of people like frontline workers and those at risk due to age or health conditions prioritised according to their vulnerability to risks.

Bush and Clinton will have priority for getting the vaccine because they are over 70, while Obama, who is 59, and has no conditions that put him at risk will be in a lower priority category.

Pfizer's vaccine is likely to get an emergency use authorisation from the Food and Drug Administration's (FDA) expert panel when it meets on December 10 and Moderna's at another meeting on December 17.

Millions of doses of the two vaccines have already been made and are ready to ship to the states within 24 hours of approval, according to officials.

The UK has already approved the Pfizer vaccine, becoming the first country after China and Russia to have a vaccine ready for the public.

The vaccines developed in less than ten months with a push from Trump and help from his Operation Warp Speed has become a source of embarrassment for President-elect Joe Biden and Vice President-elect Kamala Harris, whose administration will have to promote it if the the pandemic is to be defeated.

Harris told CNN in September that she would not trust the vaccines because the scientists and medical officials who will approve the vaccine will "be muzzled, they'll be suppressed, they will be sidelined" by Trump.

According to Gallup, the percentage of Americans willing to be vaccinated plunged from 61 per cent in mid-August to 50 per cent by mid-September, but slowly recovered to 58 per cent last month.

Biden said in October: "I trust vaccines. I trust scientists. But I don't trust Donald Trump. And at this moment, the American people can't either."

New York Governor Andrew Cuomo said that he would set up his own panel of experts to study the vaccines before allowing it in the state and not trust the federal agencies like the FDA that approves vaccines and other medicines for use by the public.

Trump had asserted that vaccines would be ready by November and this got them embroiled in elections politics.

Two companies, Pfizer and Moderna, met the deadline having gone through the Phase 3 trials, but did not announce the results showing more that 90 per cent efficacy till after the election.

It insulated them from politics, but officials of the two companies said that they weren't told of the trial results till after the election.

Now that Biden and Harris will be running the country from next month, they will have to turn around and convince the people to trust the vaccine and get at least 70 per cent of the population to get it.

Seventy per cent is the lower threshold for herd immunity, which according to scientists could also be as high as 90 per cent.

Herd immunity is a society's overall immunity to a disease that is achieved when a certain percentage of its population has built up resistance to it either through exposure to it or through vaccinations and those who are not vaccinated are also protected.

Now that Trump has confounded the sceptics by having the vaccine ready in far less time than is normal for vaccine development and even some Democrat leaders are coming around to accepting its safety and efficacy controversies haven't died down.

Cuomo has played the race card claiming that according to the Trump administration plans, African-Americans and Latinos will find it difficult to get vaccinated and at one time even threatened to sue the federal government over it.

But Trump has said that the vaccines would be given to the states according to their size and they could distribute it the way they want it.

One of the results of the entry of race politics is that the trials were criticised for not having enough African-Americans and Latinos and on Wednesday Johnson and Johnson informed volunteers that it was canceling the future participation of those who did not belong to those ethnicities.