Dr. Anthony Fauci, a senior adviser to the president on the pandemic, has tested positive for COVID-19.
Fauci, 81, hasn't had recent close contact with President Joe Biden or other senior officials, according to the National Institute of Allergy and Infectious Diseases.
Fauci, who has mild symptoms, tested positive via a rapid antigen test, according to the NIAID.
He's fully vaccinated and received two boosters, the NIAID said in a statement.
Fauci’s office told ABC News that he’s taking Pfizer’s antiviral treatment Paxlovid.
On June 11, Fauci went to the College of the Holy Cross in Worcester, Massachusetts, where the college renamed the science center the Anthony S. Fauci Integrated Science Complex. Fauci was seen with and without a mask in photos.
Fauci told CNN last month that he had never tested positive for COVID-19.
In April, Fauci notably did not attend the White House Correspondents' Dinner.
"Each of us, in our own personal way, has to make an assessment of what risk you're willing to accept about getting infected," Fauci told CNN in April. "In general, the risk is low, but I made a personal assessment. I'm 81 years old, and if I get infected, I have a much higher risk."
Fauci still plans to testify Thursday before the Senate Health committee at 9:30 a.m. on the federal response to the pandemcic. His testimony will now be virtual.
"Dr. Fauci will isolate and continue to work from his home," the statement said. "Dr. Fauci will follow the COVID-19 guidelines of the Centers for Disease Control and Prevention and medical advice from his physician and return to the NIH when he tests negative."
ABC News' Arielle Mitropoulos and Emily Shapiro contributed to this report.