The first lady announced her son's infection with the virus in a statement detailing her personal experience with the illness.
The the president and first lady tested positive for the novel coronavirus Oct. 1, and at the time, the family said Barron tested negative.
"My fear came true when [Barron] was tested again and it came up positive," Melania Trump wrote in her statement. "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."
President Trump, when asked by reporters on the South Lawn of the White House how Barron is doing, said his son is "fine."
The first lady said she experienced a "roller coaster" of symptoms with the virus, including body aches, cough, headaches and fatigue. She said she chose a "more natural route" in terms of her treatment, focusing on taking vitamins and eating healthy foods.
President Trump, meanwhile, was hospitalized at Walter Reed National Military Medical Center in Bethesda, Md., for three days after experiencing some breathing troubles. Doctors treated him with an experimental antibody cocktail by Regeneron and remdesivir, an antiviral originally created to treat the Ebola virus.
When President Trump returned to the White House after his hospitalization, the first lady revealed efforts made at the residence to protect workers, including housekeepers, butlers, chefs and florists.
In addition to installing sanitation and filtration systems at the residence and the homes of workers, the Trump family issued a mask mandate for workers in the executive mansion, implemented daily testing for those in direct contact with the family, hired additional medical support and hired a well-being consultant to focus on mental health concerns. After the Trumps tested positive for the virus, workers were required to wear full personal protective equipment.
The three members of the Trump family are among several people linked to the White House who have tested positive for the coronavirus in recent days. Many attended a Rose Garden event in which the president announced his nomination of Amy Coney Barrett to the Supreme Court.