Dr. Anthony Fauci, a public health official who became the face of U.S. government efforts to contain the coronavirus pandemic, tested positive for COVID-19 on Wednesday, the National Institutes of Health (NIH) said in a statement.

Fauci, the chief medical adviser to President Joe Biden, was experiencing mild symptoms, the NIH said in a statement. He has not recently been in close contact with Biden, it said.

The NIH said Fauci, 81, was fully vaccinated and twice boosted, and will self-isolate and continue to work from home.

The longtime director of the National Institute of Allergy and Infectious Diseases, Fauci became a popular and trusted figure during the pandemic when he served on the White House coronavirus task force under President Donald Trump.

He subsequently came under criticism from the former president and some of his Republican allies as Fauci cautioned against reopening the U.S. economy too soon, and was vilified by those opposed to COVID vaccine and masking mandates.

Trump became increasingly critical of government health officials and their guidance as a rise in infections threatened the easing of shutdown restrictions across the country in the months before the November 2020 presidential election, which he lost to Biden.