Joe Biden tested positive for Covid on Thursday, underscoring the persistence of the highly contagious virus as new variants challenge the nation’s efforts to resume normalcy after two and a half years of pandemic disruptions.

White House press secretary Karine Jean-Pierre said that Biden was experiencing “mild symptoms” and has begun taking Paxlovid, an antiviral drug designed to reduce the severity of the disease.

She said Biden “will isolate at the White House and will continue to carry out all of his duties fully during that time.

“He has been in contact with members of the White House staff by phone this morning, and will participate in his planned meetings at the White House this morning via phone and Zoom from the residence.”

Biden, 79, is fully vaccinated, after getting two doses of the Pfizer coronavirus vaccine shortly before taking office, a first booster shot in September and an additional dose March 30.

In a letter released by the White House, Kevin O’Connor, the president’s physician, described Biden’s symptoms as mild.

“Mostly rhinorrhea (or runny nose) and fatigue, with an occasional dry cough, which started yesterday evening,” O’Connor wrote. He noted that he anticipates that “he will respond favorably” to Paxlovid, as “most maximally protected patients do”.

First lady Jill Biden has tested negative, according to her office. The first lady is in Detroit for an event at a local school. Before the event started, Biden briefly addressed news of her husband testing positive for Covid.

“My husband tested positive for Covid. I talked to him just a few minutes ago. He’s doing fine, he’s feeling good,” she said. “I tested negative this morning. I am going to keep my schedule.”

The president was scheduled to deliver a speech on gun violence in Pennsylvania on Thursday. That trip has been cancelled, and he is expected to stay at his home in Wilmington, Delaware, for the weekend.

While this is Biden’s first bout of coronavirus, multiple members of his administration have contracted the virus. Vice-president Kamala Harris had Covid in April, and Xavier Becerra, the secretary of health and human services, and Antony Blinken, the secretary of state, both tested positive in May.

Coronavirus cases in the United States have been on the rise once again as the contagious BA.5 variant has become the dominant strain. The US has been recording as many as 150,000 new Covid cases a day, according to Johns Hopkins University.

In her statement, Jean-Pierre said that the White House will provide a daily update on Biden’s status “as he continues to [work] in isolation”.