Harris tested negative Tuesday, her office said.
"Earlier today, the Second Gentleman tested positive for COVID-19," Sabrina Singh, Harris’ deputy press secretary, said in a statement. "Out of an abundance of caution, the Vice President will not participate in tonight’s event. The Vice President tested negative for COVID-19 today and will continue to test."
Harris was with President Joe Biden earlier in the day for a bill signing event, while Emhoff, 57, participated in an event at the Marvin Gaye Greening Center, which hosted a team of AmeriCorps National Civilian Community Corps members. He toured the site and was joined by AmeriCorps CEO Michael D. Smith.
Biden announced Emhoff's Covid diagnosis at an event on women's equal pay Tuesday evening. He said Harris and Emhoff were feeling fine, adding that Harris was not attending the event as a precaution.
“Out of an abundance of caution she decided not to join us today, but let’s send her our love,” Biden said.
The White House said Biden tested negative Sunday in his most recent test.
Two White House officials said Biden is not considered a close contact of Emhoff, who later tweeted confirmation of his positive Covid test.
Emhoff was diagnosed just weeks after coronavirus restrictions were loosened in Washington, where a mask mandate in public schools is set to become optional Wednesday. The Biden administration last month ended mask mandates for those in the White House who were fully vaccinated.
Covid cases are down by 47 percent in the city over the past two weeks, according to figures compiled by NBC News.
Over the weekend, Biden's previous running mate, former President Barack Obama, announced he had tested positive for Covid-19.
“I’ve had a scratchy throat for a couple days, but am feeling fine otherwise. Michelle and I are grateful to be vaccinated and boosted, and she has tested negative," Obama said in a tweet.