Andrew Harnik / AP

Hillary Clinton began experiencing symptoms of what was later diagnosed as a “mild, non-contagious bacterial pneumonia” nine days before the illness forced her to leave a 9/11 memorial ceremony, her doctor wrote in a letter released by her campaign on Wednesday.

The two-page letter from Dr. Lisa Bardack added new details about Clinton’s illness and updated her medical history in the 14 months since the Democrat last provided a summary of her overall health. Bardack wrote that despite her recent setback, Clinton “continues to remain healthy and fit to serve as president of the United States.”

Clinton’s health became a sudden focus of the presidential race after she abruptly left the event commemorating the 15th anniversary of the terrorist attacks in New York and was later filmed stumbling and being helped into a van by her aides. Her campaign was initially silent on what happened and only later disclosed that Clinton had been diagnosed with pneumonia two days before the incident. Bardack confirmed that Clinton had apparently ignored her advice to rest over the weekend. She wrote that she has evaluated the Democratic nominee “several times” since September 11 and that she “continues to improve.” Clinton is scheduled to return to the campaign trail Thursday after a three-day absence.

Donald Trump has tread carefully in talking about Clinton’s condition in recent days, but he has sought to present himself as a picture of good health in contrast to her recent illness. Yet he, too, has been circumspect about releasing details of her medical records. Trump filmed an appearance with the television personality and physician Mehmet Oz on Wednesday that will be broadcast on Thursday. He reportedly showed Oz a new letter from his doctor, Harold Bornstein, whose first over-the-top description of Trump's health was widely mocked.

In her letter Wednesday, Bardack wrote that she first evaluated Clinton on September 2 after she had been experiencing “a low-grade fever, congestion, and fatigue” for the previous 24 hours. Clinton continued campaigning,her congestion worsened, and she developed a cough over the next several days. When she visited Bardack a week later, she underwent a CT scan that revealed a “small right middle lobe pneumonia.”

“She was treated with antibiotics and advised to rest,” Bardack wrote. “This was a mild non-contagious bacterial pneumonia.”

Aside from the pneumonia, Bardack also disclosed the Clinton developed a sinus and ear infection in January that required the insertion of a myringotomy tube in her left ear. She had a CT scan of her brain and sinuses in March that revealed “no abnormalities of the brain,” she wrote.

“My overall impression,” Bardack wrote, “is that Mrs. Clinton has remained healthy and has not developed new medical conditions this year other than a sinus and ear infection and her recently diagnosed pneumonia.”

The Clinton campaign also released a letter from Tim Kaine’s doctor, Brian Monahan, who pronounced the vice-presidential nominee in “overall excellent health.”

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