WASHINGTON (REUTERS) - US first lady Jill Biden has tested positive in a rebound case of Covid-19 but is not experiencing any symptoms, while President Joe Biden continues to test negative for the virus, officials said on Wednesday (Aug 24).

Jill Biden tested positive on Wednesday by antigen testing, following a negative test the previous day, and the White House's medical unit has notified close contacts, her deputy communications director said.

"The First Lady has experienced no reemergence of symptoms, and will remain in Delaware where she has reinitiated isolation procedures," her deputy communications director, Kelsey Donohue, said in a statement.

Jill Biden, 71, first tested positive for Covid-19 on Aug 16.

She had ended her first isolation on Aug 21 after a course of Paxlovid, an antiviral medication.

President Biden tested negative for Covid-19 on Wednesday morning in antigen testing, the White House said.

A White House official said the president would wear a mask for 10 days when indoors and near others.

The White House will also maintain President Biden's increased cadence of testing and report those results, the official said.