"Rest assured I expect the President to continue carrying out his duties without disruption while recovering, and I will keep you updated on any future developments", Conley concluded.
Trump says he and the First Lady are in quarantine, beginning "immediately".
"She is as smart and thoughtful as they come, a truly great person", Mr Trump said.
"As has been routine for months, Vice President Pence is tested for COVID-19 every day. In the meantime, we will begin our quarantine process!" An initial statement from the White House said both he and the First Lady were "well at this time". Hicks traveled with him on Air Force One both to Tuesday night's debate and to a rally in Minnesota on Wednesday.
"So we'll see what happens", said the president, adding that Ms Hicks often wore masks but still tested positive.
Rebels from Syria recruited to fight in Karabakh conflict
When we arrived, the soldiers were pulling pieces of what they said was an Israeli-built rocket out of the tarmac. Azerbaijan's civilian death toll has risen to 19, with 55 wounded, its prosecutor general's office said.
Trump played down the virus in its early stages and has repeatedly predicted it would go away. He has also repeatedly resisted taking precautions such as wearing a face mask, and as recently as this week mocked his Democratic opponent in the presidential race, Joe Biden, for wearing a mask. The news was reported by numerous worldwide news publications before Trump took to Twitter and confirmed the same.
This is the first time that Trump is quarantining after coming in contact with someone with COVID-19.
But Trump also bragged that he has drawn "35 to 40,000 people" at his campaign rallies, saying he brings such large crowds to outdoor events "because people want to hear what I have to say".
The development will upend Trump's campaign schedule, but it is not immediately clear if the second presidential debate scheduled for October 15 will be impacted. Trump and other Republicans and conservatives about Mr. Biden having holed himself up in a bunker.
Later, the first lady wrote on Twitter that she and her husband were "feeling good".
Hicks, one of the president's most trusted aides, previously served as White House communications director and rejoined the administration this year ahead of the election.
Vice President Mike Pence, Treasury Secretary Steven Mnuchin and Secretary of State Mike Pompeo all let it be known they had tested negative, and the White House said Supreme Court nominee Amy Coney Barrett had also been given the all-clear.