Mr Biden tested negative for the virus, the White House said on Monday evening.
“This evening, the First Lady tested positive for Covid-19," her communications director, Elizabeth Alexander, said in a statement. "She will remain at their home in Rehoboth Beach, Delaware."
Ms Biden, 72, has mild symptoms, Ms Alexander said.
The White House said that the president will test at regular intervals throughout this week and will be monitored for symptoms. He is due in New Delhi for the G20 summit beginning on Saturday.
“Following the First Lady’s positive test for Covid-19, President Biden was administered a Covid test this evening,” the White House said. “The President tested negative.”
The latest alarm over coronavirus in the White House comes ahead of a busy week for the president, packed with events including foreign visits across Asia.
The president delivered a Labour Day speech in Philadelphia earlier in the day and was scheduled to present the Medal of Honour to a Vietnam War army helicopter pilot before beginning his tour.
He is scheduled to depart for India on Thursday and hold bilateral talks with Indian prime minister Narendra Modi on the sidelines of the G20 leaders’ summit on 9-10 September.
The president will then fly to Hanoi, Vietnam and then to Alaska to mark the 22nd anniversary of the September 11 terrorist attacks.
The White House did not immediately comment on whether Mr Biden’s foreign travel would be affected by Ms Biden’s positive Covid test.
If Mr Biden were to skip the G20 summit he would become the fourth leader of the bloc to do so, after Russia’s Vladimir Putin, China’s Xi Jinping and Mexico’s Andrés Manuel López Obrador confirmed their non-attendance.
A White House administration official told CNN that there are no changes in the Covid protocols in the White House or in the president’s diary at this time.
Ms Biden last tested positive for Covid-19 in the summer of 2022 while vacationing in South Carolina. Mr Biden caught the virus a month later.
Her latest diagnosis comes amid renewed concerns over the new highly mutated BA.2.86 variant of Covid. Several countries in the world are experiencing a fourth season of rising cases of the virus since the pandemic first emerged in 2020.
In the week ending 19 August, there were approximately four fresh hospital admissions with Covid infection for every 100,000 individuals across the US, a rate categorised as low according to the US Centers for Disease Control and Prevention standards.
At least seven counties reported elevated Covid-19 hospitalisation rates, while 117 counties, equivalent to about 3.6 per cent of the country, fell within the medium threshold. Notably, a quarter of these counties were located in Florida.
The new variant, named Pirola, is the highly mutated variant of Omicron which has led to the lastest surge in cases. It was first detected in Denmark on 24 July and later in the US and Canada in August. Doctors have said the variant is unlikely to cause a severe Covid wave and death.
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