Fauci, the infectious disease expert and adviser on the nation’s COVID-19 response, told a health summit on Tuesday that his symptoms were “minimal” at first, but he was put on the antiviral drug Paxlovid when they worsened, The Hill reported.
The 81-year-old said he tested negative for three days after the five-day treatment, then tested positive again on the fourth day.
Fauci said he experienced fatigue and congestion but was “really quite well,” according to ABC News. But he felt “really poorly” during what he called the “Paxlovid rebound.” He told the summit he’s now taking a second course of the drug.
The so-called “Paxlovid rebound” has drawn the attention of the Centers for Disease Control and Prevention, which cautioned the medical community to be aware of a possible return of symptoms even more than a week after recovery.
Fauci had not previously caught the virus.
“I’m vaccinated. I’m doubly boosted,” he said in a White House teleconference on June 23 after falling ill. “And I believe if that were not the case, I very likely would not be talking to you, looking as well as I look, I think, right now.”
This article originally appeared on HuffPost and has been updated.