(CNN) Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases and member of the White House's coronavirus task force, told CNN he will begin a "modified quarantine" after making a "low risk" contact with the White House staffer who tested positive for the novel coronavirus.
The "low risk" assessment means he was not in close proximity to the person who tested positive during the time when that person was known to be positive for the virus.
He is not doing a full quarantine like Dr. Stephen Hahn, the commissioner of the Food and Drug Administration. Hahn came into contact with an individual who tested positive for coronavirus, an FDA official confirmed to CNN on Friday.
Dr. Robert Redfield, the director of the Centers for Disease Control and Prevention, will self-quarantine for two weeks after he was exposed to a person at the White House who tested positive for Covid-19, a CDC spokesperson confirmed to CNN.
Officials will not identify the person to whom Hahn or Redfield were exposed. However, Katie Miller, the press secretary to Vice President Mike Pence, tested positive on Friday. She is known to often be in the White House coronavirus task force meetings.
To err on the side of caution, Fauci said he is doing what he calls a "modified quarantine," meaning he will stay at home and telework, wearing a mask continually, for 14 days. He said he might also go to his office at the National Institutes of Health where he is the only one there. He also will be tested every day, he said, noting he was tested yesterday and was negative.
If he is called to the White House or Capitol Hill, he will go while taking every precaution, he said.
Fauci is expected to testify at a Senate hearing about the coronavirus next week. Redfield and Hahn will now testify by video conference, the committee's chairman, Sen. Lamar Alexander, confirmed on Saturday.
Fauci, though, is expected to attend while wearing a mask, a source in Alexander's office told CNN. If circumstances change and Fauci needs to testify remotely, the committee will accommodate that due to the unusual circumstances.
Meanwhile, the White House sent out an email to all staff on Friday titled, "Strong Precautions We Are Taking," about the measures the White House is taking to prevent the spread of coronavirus in the wake of Miller's positive test, an official said.
The note mostly discussed maintaining maximum telework for staff, reporting travel and monitoring one's own symptoms, according to a copy reviewed by CNN.
The memo said "high-touch points" in the White House and Eisenhower Executive Office Building, an office building near the White House where many staffers work, will receive "heightened levels of cleaning."
The day before the memo, on Thursday, White House staff received a different memo informing them that they would be asked, upon entry, about their symptoms, in addition to the temperature checks required for admission to the White House complex. Anyone who acknowledged having the symptoms may be pulled for further screening or barred entry, that memo said.
Neither memo mentioned anything about wearing facemasks.
This story has been updated with information about Fauci, Redfield and Hahn testifying before a Senate committee next week.