US Democratic vice presidential candidate Kamala Harris canceled travel plans through Sunday(18) after her communications director tested positive for Covid-19, the campaign said.
It added that Harris had not come into "close contact" with the staffer.
A non-staff flight crew member also tested positive, campaign manager Jen O'Malley Dillon said in a statement.
Harris did not need to quarantine, O'Malley Dillon added, but "out of an abundance of caution" would cancel travel and campaign virtually before hitting the road again on Monday(19).
Both individuals flew with the Democratic senator on October 8. All three were masked, O'Malley Dillon said.
Harris has conducted two PCR tests since then, both negative, the Democratic campaign said, and she had not been in contact with either individual for 48 hours before they tested positive.
She was scheduled to appear in North Carolina on Thursday, a competitive battleground state where early voting just started and Trump is due to campaign as well.
The announcement is the latest blip in a presidential campaign that has been upended by the coronavirus pandemic, and comes two weeks to the day after president Donald Trump tested positive for the disease.
Democrats especially have increased their use of virtual campaigning, fundraising and get-out-the-vote efforts to limit the spread and avoid unnecessary health risks.
Harris' husband, Doug Emhoff, planned to cancel his travel on Thursday but resume in-person events on Friday(16) since he and Harris have tested negative multiple times, the Biden campaign said.
