Three top US public health officials at the forefront of the Trump administration’s battle against the Covid-19 outbreak went into self-quarantine Saturday for the next two weeks after “low-risk” exposure to the deadly virus through contacts with someone who has tested positive.

Heads of the Centers of Disease Control and Prevention Robert Redfield and the Food and Drug Administration will be teleworking from home as a result, their spokespersons have told news publications. And Anthony Fauci, head of the National Institute of Allergies and Infections Diseases told CNN he will be going in “modified quarantine”. All three are members of the White task force on the coronavirus outbreak.

Fauci has said he will be working from home, will wear a mask and will go to office only when he will be sure to be the only one around at the time.

Fauci, Hahn and Redfield are scheduled to testify before a committee of the US senate on Tuesday, but they will now not appear in person but through a video link.

The source of their exposure was not identified.

Katie Miller, press secretary of Vice-President Mike Pence, who tested positive for Covid-19 on Friday, used to frequently attend the meeting of the task force, which is headed by her boss. She is the second White House staffer to test positive, after a US navy personnel serving as a personal valet to the president.

The White House has stepped up screening since and both the president and the vice-president are now tested every day.

At least 11 members of the US Secret Service, which protects present and past presidents, have also tested positive and 60 are in self-quarantine for possible exposure, according to news reports. It was not clear if any of them had been posted at the White House at the time of their exposure.

President Donald Trump has personally faced criticism for not following his administration’s Covid-19 protocols to wear a mask in situations were social distancing may be difficult. He met US military leaders at the White House on Saturday and did not wear a face covering, neither did any of the others.