US House of Representatives Speaker Nancy Pelosi has COVID-19 and is currently asymptomatic, after more than half a dozen other federal officials tested positive in recent days.

The Democratic leader tested positive after a negative test result earlier in the week, spokesman Drew Hammill said in a statement on Thursday (US time).

More than half a dozen senior officials, including members of Democratic President Joe Biden’s Cabinet and at least seven lawmakers, have tested positive for COVID-19 in recent days, even as caseloads drop across the country.

Ms Pelosi, 82, stood near Mr Biden briefly during a ceremony to sign a postal reform bill on Wednesday. The Centres for Disease Control and Prevention considers close contact for COVID-19 exposure to be within 1.8 metres of an infected person for 15 minutes or more.

Ms Pelosi also attended an event on the Affordable Care Act at the White House on Tuesday with Mr Biden and former US president Barack Obama.

The White House said Mr Biden, 79, had tested negative for COVID and was not considered a close contact.

Ms Pelosi is second in line to become president, behind Vice President Kamala Harris. Attorney General Merrick Garland, who is seventh in the line of succession, tested positive on Wednesday and was also asymptomatic, the Justice Department said.

A congressional delegation trip to Asia that Ms Pelosi had planned to lead had been postponed, Mr Hammill said.

“The speaker is fully vaccinated and boosted, and is thankful for the robust protection the vaccine has provided,” he said.

Ms Pelosi would quarantine according to federal health guidelines, he said.

The House continues to allow remote voting so lawmakers can casts ballots while they are in isolation.