US first lady Jill Biden has tested positive for Covid-19 again in an apparent “rebound” case, after she initially tested negative for the virus over the weekend.

President Joe Biden, who spent three days with his wife at their holiday home in Rehoboth Beach, Delaware, continues to test negative, the White House said.

He also suffered a rebound case earlier this month after an initial recovery from the virus.

Mr Biden’s deputy communications director Kelsey Donohue said the first lady “has experienced no re-emergence of symptoms, and will remain in Delaware where she has reinitiated isolation procedures”.

She added: “The White House Medical Unit has conducted contact tracing and close contacts have been notified.”

Jill Biden, 71, 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, but a minority of those prescribed the drug have experienced a rebound case of the virus a few days after their initial recovery.