Biden cleared to leave isolation following 2nd negative COVID-19 test

President Joe Biden has been cleared to break isolation now that he has tested negative for COVID-19 for the second time, his physician announced on Sunday.

An antigen test taken by Biden on Sunday produced a negative result for the second consecutive day, White House physician Dr. Kevin O'Connor wrote in a letter clearing Biden to travel.

"He will safely return to public engagement and presidential travel," O'Connor wrote in the letter.

Biden arrived in Rehoboth Beach, Delaware, on Sunday morning -- his first travel out of Washington, D.C., since late July, when he first tested positive for COVID.

The president took off his mask as he exited the White House on his way to Delaware and told reporters, “I feel good” as he headed for Marine One, adding that he was "clear" after his long isolation.

Biden tested negative for COVID-19 on Saturday after he experienced a rebound infection following his first positive test on July 21.

Biden's initial symptoms included a slight fever, cough and sore throat, among other mild symptoms. He isolated at the White House while completing a five-day course of Paxlovid, an antiviral treatment for those with mild to moderate symptoms who are considered a high risk for severe illness.

After the treatment, Biden tested negative. But the president tested positive again on July 30 in what O'Connor described as an example of "rebound positivity" from the course of Paxlovid.

Some patients who take Paxlovid can test positive again after finishing the treatment course, but those cases are uncommon. But high-risk patients who take Paxlovid still have a dramatically lower risk of being hospitalized due to the virus.

Biden and first lady Jill Biden are expected to travel to Kentucky on Monday to meet with families affected by the devastating flooding in the state that killed at least 37 people.

The visit will mark Biden's first engagement since he was diagnosed with COVID-19.

ABC News' Alexandra Hutzler and Molly Nagle contributed to this report.