Jill Biden, the First Lady, tested positive for Covid-19, the White House announced late on Monday night, but she is experiencing only mild symptoms and will remain at the family home in Rehoboth Beach, Delaware, where she and President Joe Biden spent part of the weekend.

Biden tested negative for the virus after the First Lady’s diagnosis, a spokesperson said. The president returned to the White House on Monday evening. Officials said the President would continue to test on “a regular cadence” throughout the week.

The First Lady’s diagnosis is a reminder that Covid-19 remains a potent virus in the US. Public health authorities have noted an increase in the number of Covid infections around the country, though the total number remains low.