WASHINGTON－US House of Representatives Speaker Nancy Pelosi has COVID-19 with no symptoms, her spokesman said on Thursday, after more than half a dozen other federal officials tested positive in recent days.

The 82-year-old lawmaker from California, who is second in line to the presidency, is vaccinated and boosted and is currently asymptomatic, her spokesman Drew Hammill said on Twitter.

Pelosi stood near Biden briefly during a ceremony to sign a postal reform bill on Wednesday. She also attended a White House event on Tuesday with Biden and former president Barack Obama.

Biden tested negative for COVID-19 on Wednesday evening and "will continue to be tested regularly", the White House said.

Most of the attendees at the White House events were maskless.

"The president is not considered a close contact of Speaker Pelosi as defined by the CDC. The president saw Speaker Pelosi at White House events and had brief interactions over the course of the last two days," it said in a statement.

The US Centers for Disease Control and Prevention considers close contact for COVID-19 exposure to be within 1.83 meters of an infected person for a total of 15 minutes or more within a 24-hour period.

Among those reporting a positive test on Thursday were Washington Mayor Muriel Bowser, two senators－Maine Republican Susan Collins and Democrat Raphael Warnock of Georgia－and House Democrat Angie Craig of Minnesota.

About half a dozen journalists and members of the White House staff who were at the dinner have also tested positive, according to news reports.

Vice-President Kamala Harris tested negative on Thursday, a White House official said. Harris' communications director had tested positive for COVID-19 on Wednesday.

Pelosi did not attend the annual Gridiron Club dinner, which brings together top politicians, media figures, members of the diplomatic corps and business leaders for a night of comedy.

Pelosi canceled a news conference planned for Thursday and her spokesman said a congressional visit to Asia including China's Taiwan she intended to lead has been postponed.

Zhao Lijian, spokesman of the Chinese Foreign Ministry, on Friday expressed his sympathy over Pelosi's infection and wished her a speedy recovery.

However, Zhao said at a daily news briefing that Pelosi should have canceled her Taiwan trip immediately instead of delaying it.

China has made its position clear on the issue as Beijing said on Thursday it would take strong measures if Pelosi visited Taiwan on her trip, in response to reports she was planning to go.

The total number of COVID-19 cases in the United States has exceeded 80 million, with 984,000 related deaths, according to the latest data from Johns Hopkins University.

Anthony Fauci, a top US infectious disease expert, said on Wednesday that he expects the BA.2 subvariant of the coronavirus to fuel an increase in COVID-19 cases across the US.

"I would not be surprised if we see an uptick in cases," Fauci said in an interview on Bloomberg Television.

Agencies - Xinhua