Vice presidential nominee Kamala Harris will suspend in-person events until Monday after two staff members associated with the Democratic campaign tested positive for Covid-19.
Joe Biden's team said the presidential hopeful had had no exposure, although he and Ms Harris spent several hours campaigning together in Arizona last week.
Ms Harris was scheduled to travel to North Carolina on Thursday evening for events encouraging voters to cast early ballots.
The campaign told reporters that Ms Harris’ communications director and a traveling staff member for her travel to Arizona tested positive.
Ms Harris and Mr Biden spent several hours together that day through multiple campaign stops, private meetings and a joint appearance in front of reporters at an airport.
They were masked at all times in public, and aides said they were masked in private, as well - and the pair have each had multiple negative tests since then.
Meanwhile, it was revealed on Wednesday that Donald Trump's teenage son Barron had contracted Covid, but has since tested negative for the respiratory disease.
In a statement entitled "my personal experience with Covid-19", first lady Melania Trump revealed the couple's son initially tested negative before then testing positive for the virus.
She went on to say he has since, once more, tested negative.
The first lady said the 14-year-old had shown "no symptoms" adding: "Luckily he is a strong teenager."