First lady Jill Biden tested negative for COVID-19 on Monday and will return to Washington on Tuesday, nearly a week after she came down with a "rebound" case of the coronavirus.

Her communications director, Elizabeth Alexander, announced the negative test in a statement Monday night.

Jill Biden had been isolating at her family's house in Rehoboth Beach, Delaware, since testing positive on Aug. 24, and at the time, her spokesperson said she was not experiencing any symptoms. She first tested positive for the virus on Aug. 15, when she and President Joe Biden were vacationing in Kiawah Island, South Carolina.

The president, who had his own back-to-back cases of COVID-19, was identified as a close contact of his wife and the White House said he was undergoing more frequent testing for the virus as a precaution. While Centers for Disease Control and Prevention guidelines called for Biden to wear a face covering in close proximity to others indoors, he was seen without a mask hugging and taking selfies with supporters during an indoor rally on Thursday in the Washington suburbs.

Jill Biden, 71, and her husband, 79, have been twice-vaccinated and twice-boosted with the Pfizer COVID-19 vaccine. She had been prescribed the antiviral drug Paxlovid, which has proven to be highly effective at preventing serious disease and death among those at highest risk from COVID-19. A minority of those prescribed the drug have experienced a rebound case of the virus a few days after their initial recovery.