Although COVID-19 has claimed more than 207,000 lives, many people who become infected by the virus show only mild symptoms, or none whatsoever. She had traveled with the president several times in the past week.
"We are feeling good & I have postponed all upcoming engagements".
The development almost a month ahead of the US Presidential elections could alter the course of the polls dramatically. Treasurys are rallying after the president's positive COVID-19 test.
Other top White House aides have tested positive for the coronavirus in recent months, including a valet for Trump; Katie Miller, a top press aide to Vice President Mike Pence; and National Security Advisor Robert O'Brien. Hicks is considered one of the president's closest allies and traveled with him on Air Force One both to Tuesday night's debate and to a rally in Minnesota on Wednesday.
He also called Hicks a "warm" person with military members and "it's very hard to say 'stay back'".
The Washington Post reports that after White House officials learned of Hicks' symptoms, Trump and his entourage flew to New Jersey for a fundraiser and speech, where Trump was in contact with dozens of others.
Ms Hicks was pictured getting off the presidential jet on Tuesday in Cleveland without a mask.
In what has become an overtly political gesture, Trump nearly never wears a mask in public - an example followed by his supporters and many of his aides.
WHO, partners roll out rapid COVID-19 tests for poor nations
Tuite said it is important to know antigen tests do have limitations, because they don't amplify the virus the way PCR tests do. This is a way to sort of standardize that, systemize it and put it out in a guidance document where it's publicly available".
He also suggested she may have contracted it from well-wishing supporters. We've done a great job. And you get close.
Days later, Mr Trump spoke in front of hundreds of people on the South Lawn of the White House at a signing ceremony for diplomatic accords between the United Arab Emirates, Bahrain and Israel.
Trump's official physician, Sean Conley, said in a statement that the president and his wife "are both well at this time".
More than 200, 000 Americans have died from the coronavirus, with millions infected.
The couple seen together at the first Presidential debate.
The White House issued a new schedule for Trump's activities on Friday that did not include a planned trip to Florida.
Twitter pundits leaned on the karma narrative, pointing out that Trump had teased Joe Biden for his own mask-wearing just two nights earlier at the Presidential Debate, where Trump's family sat unmasked and undistanced in the audience.
Trump has spent much of the year downplaying the threat of the virus, rarely wearing a protective mask and urging states and cities to "reopen" and reduce or eliminate shutdown rules. Every time you see him he wears a mask. Trump and other Republicans and conservatives about Mr. Biden having holed himself up in a bunker.