Anthony Fauci, the government's top infectious-disease expert and President Joe Biden's chief medical adviser, tested positive for coronavirus on Wednesday, according to a joint statement from the White House and health officials.

Fauci, 81, who has received two doses of the Moderna vaccine and two booster shots, diagnosed himself after taking a rapid antigen test. He had not previously tested positive for the virus.

The statement said that Fauci had not recently been in close proximity to Biden or other senior officials. He is experiencing mild symptoms and will isolate and continue to work from his home.

Fauci said in April that the United States has moved out of the "full-blown pandemic phase" of fighting the coronavirus, as vaccines and antiviral treatments have limited complications and deaths from contracting an infection. But he has continued to warn of the continuing risks from the virus, and in late April backed out of attending the White House correspondents' dinner, saying that it was his "personal choice" to skip the event, which drew about 2,000 attendees.

Fauci had been slated to testify at a Senate health panel on Thursday morning about the state of the federal government's coronavirus response.

Neither Fauci, nor the White House immediately responded to requests for more information.

About half the president's Cabinet have shared positive diagnoses in recent months, Health and Human Services Secretary Xavier Becerra this week tested positive for the virus for the second time in a month. Others who have announced infections include Interior Secretary Deb Haaland, Attorney General Merrick Garland and Commerce Secretary Gina Raimondo. None of the officials experienced severe symptoms, and all recovered quickly.

The Washington Post's Yasmeen Abutaleb contributed to this report.