Doug Emhoff, the US second gentleman, has tested positive for Covid-19, the White House announced on Tuesday.
The vice-president, Kamala Harris, tested negative, but is curtailing her schedule as a result of her husband's positive test.
Harris's spokesperson Sabrina Singh said Harris would not participate in a planned Equal Pay Day event on Tuesday evening at the White House with Joe Biden "out of an abundance of caution".
"The vice-president tested negative for Covid-19 today and will continue to test," she said.
Biden and Harris appeared together on Tuesday afternoon and mingled with lawmakers at an event marking the signing of a $1.5tn government funding measure.
"He's feeling very well, I'm told," Biden said on Tuesday evening at the event, noting Harris had to skip. "Let's send her our love," he told attendees.
Harris and Emhoff both received their first dose of the Moderna vaccine weeks before taking office and their second dose just days after inauguration day in 2021. They received booster shots in late October.
Fully vaccinated and boosted people have a high degree of protection against serious illness and death from Covid-19, particularly the most common and highly transmissible Omicron variant.
Earlier on Tuesday, Emhoff participated in an outdoor event at a Washington park to highlight the work of AmeriCorps National Civilian Community Corps.
The White House did not immediately respond when asked if he was recently in close contact with Biden or the first lady, Jill Biden.
Before Emhoff's diagnosis was public, the White House press secretary, Jen Psaki, said that the president had tested negative for Covid-19 on Sunday.