Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has started what he called a "modified quarantine" after he came in contact with a White House staffer, who tested positive for COVID-19, according to CNN, making him the third senior U.S. health official to go into self-isolation. 

But the member of the White House's coronavirus task force said he was not in close proximity to this person with the virus, adding he's at "low risk" and the test result came out negative on Friday.

It's not immediately clear which White House staffer Fauci had contacted with.

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COVID-19 hits White House staff close to the president and his inner circle

Two other cabinet-level U.S. officials, Director of the Centers for Disease Control and Prevention Robert Redfield and U.S. Food and Drug Administration Commissioner Stephen Hahn, were both in self-quarantine after coming into contact with someone who had tested positive for COVID-19.

Fauci told CNN on Saturday that he will stay at home and telework - though he might go to his office at National Institute of Allergy and Infectious Diseases, as he is the only one there - and wear a mask continually for 14 days.

According to U.S. media, the CDC and FDA chiefs are to attend Senate hearing about the coronavirus on Tuesday and testify remotely due to their special situations while Dr. Fauci plans to attend as of now while wearing a mask.

(Cover: Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases, listens as U.S. President Donald Trump answers questions during the coronavirus task force daily briefing at the White House in Washington, U.S., March 25, 2020.)