Barron recovered and tested negative afterward.
"Naturally my mind went immediately to our son," Melania wrote in a statement released by the White House. "To our great relief he tested negative, but again, as so many parents have thought over the past several months, I couldn’t help but think 'what about tomorrow or the next day?'"
"My fear came true when he was tested again and it came up positive," she added. "Luckily he is a strong teenager and exhibited no symptoms. In one way I was glad the three of us went through this at the same time so we could take care of one another and spend time together. He has since tested negative."
Both his parents, along with several White House officials, tested positive for the virus in recent weeks. President Trump was taken to Walter Reed hospital in Bethesda, Maryland, earlier this month before he was released and later cleared by White House physician Sean P. Conley to attend public events again after testing negative. Melania Trump has been recovering in the White House.
The first lady said she had "minimal symptoms," although they "hit me all at once and it seemed to be a roller coaster of symptoms in the days after."
"I experienced body aches, a cough and headaches, and felt extremely tired most of the time. I chose to go a more natural route in terms of medicine, opting more for vitamins and healthy food," her update read. "We had wonderful caretakers around us and we will be forever grateful for the medical care and professional discretion we received from Dr. Conley and his team. It was an unfamiliar feeling for me to be the patient instead of a person trying to encourage our nation to stay healthy and safe."
The first lady added that she recently tested negative for the virus.
"Along with this good news, I want people to know that I understand just how fortunate my family is to have received the kind of care that we did. If you are sick, or if you have a loved one who is sick—I am thinking of you and will be thinking of you every day," she said. "I pray for our country and I pray for everyone who is grappling with COVID-19 and any other illnesses or challenges."
Other than the president, first lady, and their son, none of the other Trump family members—including Ivanka Trump and White House adviser Jared Kushner—have tested positive for the virus.