In truth, the nation’s leading infectious-diseases expert never really went away. But after enduring nearly a year of darts and undermining comments from former President Donald Trump, Dr Anthony Fauci now speaks with the authority of the White House again.

He called it “liberating” Thursday to be backed by a science-friendly administration that has embraced his recommendations to battle COVID-19.

“One of the new things in this administration is, If you don’t know the answer, don’t guess,” Fauci said in one pointed observation during a White House briefing. “Just say you don’t know the answer.”

“The idea that you can get up here and talk about what you know and what the science is ... it is something of a liberating feeling,” Fauci told reporters.

While choosing his words carefully, Fauci acknowledged that it had been difficult at times to work for Trump, who repeatedly played down the severity of the pandemic, refused to consistently promote mask-wearing and often touted unproven scientific remedies, including a malaria drug and even injecting disinfectant.

“It was very clear that there were things that were said, be it regarding things like hydroxychloroquine and other things, that really was uncomfortable because they were not based in scientific fact,” Fauci said. He added that he took “no pleasure” in having to contradict the president, a move that often drew Trump’s wrath.

His day began with a 4am virtual meeting with officials of the World Health Organisation, which is based in Switzerland, and stretched past a 4pm appearance at the lectern in the White House briefing room.

The breakneck pace showcased the urgent need to combat a pandemic that has killed more than 400,000 Americans and reached its deadliest phase just as the new president comes to office.

Fauci made clear that he believed the new administration would not trade in the mixed messages that so often came from the Trump White House, where scientific fact was often obscured by the president’s political agenda.

In the afternoon, the doctor chatted with reporters and then stood alongside Biden and Vice President Kamala Harris in the White House as they unveiled a series of executive orders aimed at slowing the spread of the virus.

It was all a stark contrast after to the Trump administration, which blocked most of Fauci’s media briefings. The doctor went from being a constant presence in the briefing room during the first weeks of the pandemic to largely being banished as Trump grew jealous of the doctor’s positive press and resentful of Fauci’s willingness to contradict him.

Moreover, Trump frequently undermined Fauci’s credibility, falsely insisting that the pandemic was nearly over. The president regularly referenced Fauci’s early skepticism about the effectiveness of masks for ordinary Americans, a position that Fauci quickly abandoned in the face of more evidence. And he even made fun of Fauci’s first pitch at a Washington Nationals game.

The president’s attacks on Fauci — and his dismissiveness of the science — handicapped medical professionals trying to get Americans to take the virus seriously.

“There was clear political influence on the message of the pandemic. It became political to say that the pandemic was devastating our community because it was interpreted as a judgement on Trump,” said Dr. Nahid Bhadelia, an infectious-diseases physician and a professor at the Boston University School of Medicine. “It actively created enemies of the public health folks in a segment of the population.“

Having Fauci return to a central role, Bhadelia said, is a sign “that science was being repressed and now back.“