The Trump administration has barred Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, from speaking publicly about the novel coronavirus without approval, according to The New York Times.

Fauci is one of the top experts in the US on infectious diseases, and his sober public messages have contrasted with President Donald Trump's optimistic claims about the impact of the illness.

An NIAID spokesperson told Business Insider the claim in the Times report is "not true."

Experts have criticized the Trump administration for effectively muzzling Fauci with the US facing its most serious public-health crisis in years.

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Editor's note (March 24): In the weeks since this article's publication on February 28, Dr. Anthony Fauci appears to have been communicating more freely and has regularly spoken alongside the president and given interviews.

President Donald Trump's administration has barred one of the top US experts on infectious diseases from speaking out about the coronavirus outbreak without permission from the White House, The New York Times reported Thursday, in an apparent bid to stop contradictory messages about the public-health crisis.

At a Wednesday press conference, Trump announced that Vice President Mike Pence — who has faced criticism for his handling of an HIV outbreak as Indiana governor — would lead US efforts to halt the spread of the illness and that Pence would report directly to Trump.

Read more: The CDC outlined an ominous hypothetical scenario of what could happen next as the coronavirus spreads

Among the first steps Pence took was to institute measures to coordinate messaging, which would require top officials to seek clearance before making public statements on the illness.

Vice President Mike Pence and President Donald Trump at Wednesday's press conference about the coronavirus. REUTERS/Carlos Barria

Those officials included Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases. He told associates the White House "had instructed him not to say anything else without clearance," The Times said.

"This is not true," said a NIAID spokesperson of the report, in an emailed statement to Business Insider.

Fauci has led the institute — a federal agency focused on researching infectious diseases — since 1984, and he has a key role in coordinating efforts on global health issues, according to the agency's website.

He has also advised six presidents on domestic and global health issues such as HIV and AIDS.

Fauci with then-President Barack Obama on a tour of the Vaccine Research Center at the National Institutes of Health in Bethesda, Maryland, in 2014. Larry Downing/Reuters

Fauci's public remarks have been at odds with the president

Fauci's public remarks on the novel coronavirus in recent days have struck a markedly different tone from those delivered by Trump, who has played down the likely impact of the illness COVID-19 and is reportedly concerned that negative messages from public officials will spook financial markets.

In an interview with CNBC on Tuesday, Fauci warned that travel restrictions, such as those introduced by the Trump administration for some visitors from China, would become "irrelevant" if the coronavirus became a pandemic because "you can't keep out the entire world."

He also told CNN last week that the world was on the brink of a coronavirus pandemic.

Trump on Wednesday said the US was "rapidly developing a vaccine" for the coronavirus and "will essentially have a flu shot for this in a fairly quick manner." But in an interview with Fox News on Tuesday, Fauci had said the process of developing a vaccine could take up to a year and a half.

"Even though we are going as fast as you possibly can, it's still going to take a good year, year and a half to see if we have a vaccine that works," he said.

'An effort to muzzle fact and science'

Health and national security experts have criticized the Trump administration for stopping one of its top public-health officials from speaking freely as the US faces its worst public-health crisis in years.

Ned Price, a top National Security Council aide under the Obama administration, tweeted Thursday: "During the Ebola outbreak, we couldn't get enough of @NIH's Dr. Fauci because no one knew more or could deliver it with more authority or experience. Muzzling Dr. Fauci is an effort to muzzle fact and science when it's needed most."

"Presidents Reagan, Bush, Clinton, Bush and Obama trusted Tony Fauci to be their top adviser on infectious disease, and the nation's most trusted communicator to the public," Ronald Klain, who led the Obama administration's response to the 2014 Ebola crisis, also said.

"If Trump is changing that, it is a threat to public health and safety."