House Speaker Nancy Pelosi, D-Calif., has tested positive for COVID-19, her spokesperson said Thursday.

"After testing negative this week, Speaker Pelosi received a positive test result for COVID-19 and is currently asymptomatic," Pelosi's deputy chief of staff Drew Hammill said in a Twitter post on Thursday. "The Speaker is fully vaccinated and boosted, and is thankful for the robust protection the vaccine has provided."

"The Speaker will quarantine consistent with CDC guidance, and encourages everyone to get vaccinated, boosted and test regularly," Hammill added.

Pelosi stood next to President Joe Biden during a bill signing on Wednesday and also attended another White House event with Biden and former President Barack Obama on Tuesday, but the White House press office on Thursday said Biden was not a close contact because they were "brief interactions."

President Biden also tested negative for COVID-19 on Wednesday night, according to the press office.

Asked whether the president will be tested more frequently due to the growing number of COVID cases in Washington and among top officials, the White House's top spokeswoman said the decision would be up to his doctor but did not signal a change.

Press secretary Jen Psaki added that the president does not seem concerned about the growing number of cases in his orbit.

"COVID-19 will continue to be with us, and we will see cases rise and fall," she said. "The most important message we're sending to the public is that we have steps in place that we can take to continue to address it."

Biden is tested "a couple of times" per week, and so is anyone who is scheduled to be in close contact with him at the White House.

"He knows there are a number of steps and precautions that we put in place and we take to protect him and protect the Vice President and other senior members of the team," Psaki said.

In a subsequent statement on social media, Pelosi expressed gratitude for concern over her health and encouraged Americans to get vaccinated. 

"I tested positive for COVID and am asymptomatic. Thank you for your many kind wishes," the tweet, signed with Pelosi's initials, "NP," read in part. "I am grateful for them and to be vaccinated. Please get vaccinated and boosted if you haven’t already. COVID is still a public health challenge. Let’s keep up the fight to protect our care."

The California Democrat is the latest – and highest-ranking – prominent Washington, D.C., figure to test positive for COVID-19 in recent days. 

Attorney General Merrick Garland, Commerce Secretary Gina Raimondo and Reps. Adam Schiff, D-Calif., Katherine Clark, D-Mass., and Joaquin Castro, D-Texas, all announced Wednesday they had tested positive for the virus on Wednesday. All but Clark had attended the Gridiron Dinner, a high-profile D.C. media event. Pelosi was also not in attendance at the dinner.

Washington, D.C., Mayor Muriel Bowser also announced Wednesday she tested positive for COVID-19 and will "work at home while following isolation protocols." She did also not attend the Gridiron Dinner, per her office.

A planned Congressional delegation trip to Asia led by Pelosi set for the House's two-week Easter recess has been postponed, Hammill said. Her Thursday morning press conference was also called off.

Pelosi is second in the presidential line of succession behind Vice President Kamala Harris.

This is a developing story. Check back later for further updates.