Top US infectious disease expert Anthony Fauci has finally aired some of his grievances about former president Donald Trump.

Dr Fauci revealed he was often sidelined or silenced by his former boss, who infamously suggested bleach as a coronavirus cure.

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At a White House news briefing on Thursday (Washington time), Dr Fauci was asked about ‘jokes’ he had made and whether he felt less constrained under the new administration.

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He then said he took “no pleasure” in contradicting the former president and felt during the last year there were “repercussions” when he did so.

Despite the intimidation, sometimes he was forced to contradict as a matter of public safety, which put him in the firing line.

“It was very clear that there were things that were said regarding things like hydroxychloroquine and other things like that, that was uncomfortable because they were not based on scientific fact,” he said.

After being repressed during the first year of the pandemic, Dr Fauci revealed it was “liberating” to work with the Biden administration and be free to let the science do the talking.

“The idea that you can get up here and talk about what you know, what the evidence and science is, and know that’s it – let the science speak – it is somewhat of a liberating feeling,” he said.

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Dr Fauci also said based on recent seven-day averages, coronavirus infections may be about to hit a plateau in the United States.

He also explained coronavirus vaccines could be modified to account for new variants of the virus, and while the South Africa variant was concerning, it did not appear to be in the United States.

COVID-19 has spiralled out of control for months, with the US death toll exceeding 400,000.

Dr Fauci received his first dose of the COVID-19 vaccine at the National Institutes of Health in December.

Dr Fauci said he expected current vaccines would be effective against the recently discovered virus mutations.

“Bottom line: We’re paying very close attention to it for our alternative plans if we have to ever modify the vaccine,” he said.

“But right now, from the reports we have … it appears that the vaccines will still be effective against them.”

• Related: Biden tackles pandemic on first full day as POTUS

New president, new pandemic approach

Dr Fauci was tasked by President Joe Biden to give an update on the pandemic after largely being sidelined in recent months by former president Donald Trump.

Dr Fauci said the new administration would “be completely open and honest” in dealing with the pandemic and, in an implicit rebuke to the Trump administration, said everything now would be “based on science and evidence”.

He also said in the Biden administration, the rule would be “if you don’t know the answer, don’t guess”.

Mr Biden is poised to ramp up America’s vaccination program, expand testing and mask-wearing, safely reopen schools and businesses and advance racial equity.

His plan aims to increase vaccinations by opening up eligibility for more people such as teachers and grocery clerks.

Love for ‘liberated’ Dr Fauci

The public response to Dr Fauci’s more relaxed demeanour when discussing the United States’ new approach to tackling the coronavirus pandemic was overwhelmingly positive.

Many Twitter users pointed out how much happier he seemed, with @therecount posting a side-by-side video of Dr Fauci at the Joe Biden briefing and at a Donald Trump briefing.

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Many Twitter users noted how much younger and more relaxed he looked during his Thursday briefing, with some conveying their excitement at the adults being “back in charge”.

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The US will remain part of the World Health Organisation (WHO) and join the COVAX program to supply vaccines to poor countries under the Biden administration, according to Dr Fauci.

Mr Trump had previously halted funding to the WHO, to whom the United States is the largest donor, and announced a process to withdraw from the agency by July 2021.

-with agencies