U.S. President Joe Biden’s condition since contracting COVID-19 has improved considerably and his greatest symptom now is a sore throat, his physician said on Sunday.

Biden’s cough and body aches have diminished since he tested positive for the coronavirus on Thursday and he is not experiencing any shortness of breath, the physician, Dr. Kevin O’Connor, said in a memo released by the White House.

“His symptoms continue to improve significantly. His predominant symptom now is sore throat. This is most likely a result of lymphoid activation as his body clears the virus, and is thus encouraging,” O’Connor said. Biden’s pulse, blood pressure, respiratory rate and temperature all were normal.

“His voice remains a bit deep,” O’Connor said.

Earlier on Sunday, White House COVID coordinator Ashish Jha said in interviews on “Fox News Sunday” and ABC’s “This Week” that none of Biden’s 17 identified close contacts had so far tested positive for the coronavirus.

Biden, 79, has had mild symptoms since his diagnosis, which came as a highly contagious subvariant of the coronavirus drives a new wave of cases in the United States. On Saturday, O’Connor said genomic sequencing found that subvariant, known as BA.5, was likely the cause of Biden’s illness.

Jha told CBS’s “Face the Nation” on Sunday that Biden had an upper respiratory infection.

The White House has sought to underscore Biden’s ability to work through his illness. On Thursday, it released a video of him reassuring Americans he was doing fine, and on Friday he participated in virtual meetings with White House staff.

The president had no public events over the weekend, and travel plans for the early part of this week have been canceled.

Biden’s diagnosis came as political and economic challenges confront his presidency, with his policy agenda under threat on Capitol Hill and high inflation hurting his approval rating with voters, who will decide at polls in November whether Republicans or Democrats control Congress.

Biden’s Democrats currently have a slim majority in the House of Representatives and control the evenly divided Senate through Vice President Kamala Harris’ tie-breaking vote.