(CNN) — Vice President Kamala Harris tested positive for Covid-19 on Tuesday after returning from a weeklong trip to California.

“Today I tested positive for COVID-19. I have no symptoms, and I will continue to isolate and follow CDC guidelines. I’m grateful to be both vaccinated and boosted,” Harris tweeted Tuesday afternoon.

Kirsten Allen, the vice president’s press secretary, said in an earlier statement that Harris tested positive for Covid-19 on rapid and PCR tests. Harris “will isolate and continue to work from the vice president’s residence,” Allen said.

“She has not been a close contact to the President or First Lady due to their respective recent travel schedules. She will follow CDC guidelines and the advice of her physicians. The Vice President will return to the White House when she tests negative,” she added.

Harris had been scheduled to receive her intelligence briefing at 10:15 am ET Tuesday at the White House alongside President Joe Biden, according to daily guidance sent to reporters Monday evening. She did not participate in any events or meetings at the White House on Tuesday, according to a White House official.

Contact tracing is underway, a White House official said. Officials will notify the appropriate people, but as of Tuesday afternoon, the office had not identified close contacts among staff.

A handful of staff members traveled with Harris to California last week, including deputy chief of staff Mike Fuchs and national security adviser Phil Gordon. It’s unclear whether all staff members listed stayed in California with Harris through the duration of her weeklong trip.

Biden and Harris spoke over the phone on Tuesday afternoon, according to the White House.

“He wanted to check in and make sure she has everything she needs as she quarantines at home,” a White House statement to reporters said.

Harris’ isolation will have immediate impact on Senate Democrats. Democratic Sens. Chris Murphy of Connecticut and Ron Wyden of Oregon both also announced they had tested positive as well on Tuesday, meaning that their absences — along with Harris — will delay Democrats’ plans to confirm a pair of high-profile nominees this week, a senior Democratic aide told CNN.

Senate Majority Leader Chuck Schumer hoped to confirm Lisa Cook to be a member of the Federal Reserve Board and Alvaro Bedoya to be the chair of the Federal Trade Commission. But because there is broad Republican opposition to them, votes to process those nominations will be put off until Democrats, who narrowly control the 50-50 chamber, are back to full strength.

In a sign of the partisan combativeness that is so prevalent in the Senate, Republicans will still force a procedural roll call vote on Cook’s nomination — which will fail — later Tuesday and force Democrats to go through the process of breaking a filibuster against her again. GOP senators could have given consent to waive the actual vote but didn’t. Republicans have not said yet if they would do the same with Bedoya’s nomination.

The Senate is set to confirm Lael Brainard to be the vice chair of the Fed Tuesday afternoon. Her nomination is not affected by the absences because she has bipartisan support.

Harris not a close contact of Biden

Harris arrived at the White House Tuesday morning, a White House official told CNN, and went straight to take a test. After testing positive on both PCR and rapid tests, she returned home to her residence at the Naval Observatory, where she will be isolating.

Separately, an official said Harris last saw Biden at the Easter Egg Roll on April 18. She left Washington for California that afternoon and didn’t return until Monday night.

While in California last week, she held events on portfolio issues. In San Francisco on Thursday, Harris highlighted the Black maternal health crisis during events and was indoors talking to expecting mothers and health providers without a mask on. Masks are recommended, but no longer required, in most public indoor spaces in the city.

Harris held no public events over the weekend before returning to the nation’s capital.

One official said Harris tested negative through her “regular” testing up until Tuesday. CNN has asked when the vice president last tested negative.

Harris completed her two-dose regimen of the Moderna Covid-19 vaccine in January 2021. She received her first booster dose in late October and a second booster vaccine on April 1.

Covid makes its way through elite Washington

The vice president’s positive Covid-19 test comes as the US has largely lifted most of its Covid-19 mitigation measures after the Omicron variant spike over the winter.

In accordance with federal public health guidelines, officials and visitors have not been required to wear masks or socially distance at large White House events. Covid cases in Washington have declined since their peak in early January, when the country was facing a wave of Omicron variant cases, but have been rising recently.

Though the White House has continued to hold crowded indoor events where masks are optional and officials have forgone masks in public, the administration has said they are going beyond federal guidelines to detect Covid-19 in the building. There’s mandatory testing for those who come into contact with Biden and social distancing during meetings, at least when it’s possible.

White House press secretary Jen Psaki said in early April that the White House was not considering returning to pandemic-era restrictions.

“We are continuing to implement the return-to-work policy and feel we have the measures necessary to do that,” she said at the time.

Officials have acknowledged that it’s “possible” Biden will eventually contract the virus as Covid-19 has also been making the rounds among White House staff and among the Washington elite recently.

In late March, White House press secretary Jen Psaki cancelled her plans to travel with the President to Belgium and Poland after testing positive for Covid-19 for the second time. Her replacement on the Europe trip, White House principal deputy press secretary Karine Jean-Pierre, tested positive shortly after returning from the trip. Harris’ husband, second gentleman Doug Emhoff, tested positive for Covid-19 earlier in March.

Following the Gridiron Club Dinner, an annual event with members of the press and prominent Washington officials that was held in early April, dozens of attendees tested positive, including two Cabinet members and Harris’ communication director, Jamal Simmons. He was considered to be a close contact of the vice president. Harris was criticized in the wake of that close contact for her seeming disregard of US Centers for Disease Control and Prevention masking guidance for those who were exposed to Covid-19, as she did not wear a mask during the Supreme Court confirmation vote for Judge Ketanji Brown Jackson.

This story has been updated with additional reporting.

Vice President Kamala Harris tests positive for Covid