Dr. Anthony Fauci, someone millions of Americans are trusting to help them deal with the coronavirus crisis, has now had to be given increased security after threats to his safety, a source familiar with the matter told ABC News.

The source did not reveal the nature of the threats against Fauci, director of the National Institute of of Allergy and Infectious Diseases at the National Institutes of Health.

In recent days, on the recommendation of the U.S. Marshals Service, the department approved a special deputization request from HHS for more than a half dozen HHS inspector general special agents to provide protective services for Fauci.

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Law enforcement officials tell ABC News that a security assessment for Fauci was conducted after a wave of threats in the past weeks were posted online about him, including at least one direct threat to Fauci threatening harm to him and his family.

Another factor for approving the protection, one official added, was that Fauci in recent weeks has also been approached in public by admirers who were getting too close for comfort, asking for things like autographs and selfies, and there was a desire to get a protective bubble around him for social distancing purposes as well as security.

The HHS OIG's office, which is tasked with providing Fauci's detail, has provided the following statement to ABC:

"For more than two decades, the Office of Inspector General has provided professional protective services for the HHS Secretary and, as needed, to Departmental leadership. In each case, OIG assesses and recommends the appropriate level of protection. Dr. Fauci’s standard of protection is consistent with that provided to HHS officials in previous administrations. Due to the sensitive nature of protective operations, no further details can be provided at this time.

As Fauci has become one of the more prominent national faces for the Trump administration's response to the coronavirus, some in far-right or fringe conspiracy websites have baselessly sought to cast him as a member of the 'deep-state' resistance out to undermine Trump.

Facebook posts have re-surfaced a series of emails in 2012 and 2013 from Fauci sent to aides of then-Secretary of State Hillary Clinton -- part of a WikiLeaks dump of emails believed to be hacked by Russian operatives, in which Fauci expressed admiration for Clinton.

The criticism, however, doesn't appear yet to have had a major impact on President Trump's thinking towards Fauci. Even as Fauci has publicly corrected Trump in several instances related to the pandemic, Trump has described Fauci as "extraordinary" and "fantastic" in interviews and briefings at the White House.

At the White House briefing on the crisis Wednesday, with Fauci standing nearby, Trump said, "He doesn't need security. Everybody loves him. Besides that, they'd be in big trouble if they ever attacked him."

The security threat assessment was done by HHS law enforcement and security officials. The U.S. Marshals signed off on their request to deputize Office of Inspector General agents to protect Fauci and after that, the Justice Department signed off on the request.

HHS OIG agents received special deputations by USMS to provide protective services to Fauci, according to a U.S. Marshals Service official.

When asked about the increased security on NBC's "Today" show Thursday morning, Fauci said it's all part of the job.

"I've chosen this life. I mean, I know what it is. There are things about it that sometimes are disturbing. But you just focus on the job you have to do. And just put all that other stuff aside and try as best as possible not to pay attention to it. And just forge ahead. We have a really, really, very, very difficult situation ahead of us. All of that other stuff is secondary," he said.

Facui who's 79 and still a runner, has been open about his increased work load and the toll it takes.

“It’s grueling. Um, in some respects I think it would probably be almost unsustainable. But I’m just, as I often say, just sucking it up cause because you got to do it," Fauci said in an interview posted on the NIH website on Friday.

In that recorded interview with his NIH boss, Fauci joked about getting to the White House via the Washington D.C. Metro system.

“When the White House heard that, they went completely nuts,” Fauci said with a hearty laugh.

What to know about coronavirus:

How it started and how to protect yourself: coronavirus explained

What to do if you have symptoms: coronavirus symptoms

Tracking the spread in the US and Worldwide: coronavirus map