U.S. President Joe Biden's COVID-19 symptoms have improved since he started taking an antiviral drug, his physician Kevin O'Connor said Friday, a day after the 79-year-old tested positive for the novel coronavirus.

"President Biden completed his first full day of Paxlovid last night," O'Connor said in a memorandum, referring to the oral COVID-19 pill developed by Pfizer Inc. "His symptoms have improved," the doctor said.

U.S. President Joe Biden gives the thumbs up while reacting to questions from the press about how he is feeling, while participating virtually in a meeting with his economic team in the South Court Auditorium of the White House campus July 22, 2022 in Washington. (Getty/Kyodo)

On whether the diagnosis will affect envisioned talks with Chinese President Xi Jinping, which Biden said on Wednesday would occur within 10 days, White House Press Secretary Karine Jean-Pierre told a press conference, "We'll see how the president does."

Biden has had no fever, although his temperature rose to as high as 37.4 C on Thursday evening, according to Ashish Jha, COVID-19 response coordinator for the White House. His symptoms continue to be a runny nose and fatigue, with an occasional cough.

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"His pulse, blood pressure, respiratory rate and oxygen saturation remain entirely normal," the memorandum said.

Biden tested positive Thursday morning and has been experiencing mild symptoms. He has been able to continue working despite the diagnosis, and noted that he has put in over eight hours a day, according to Jean-Pierre.

The president is fully vaccinated and has received two booster shots for additional protection.