President Woodrow Wilson, far right, stands with other world leaders outside the World War I Peace Conference in Paris in May 1919. He had suffered from the flu there the month before. Library of Congress

WASHINGTON — In the fall of 1918, as President Woodrow Wilson scrambled to end World War I, the flu pandemic began its lethal march across the country, killing at least 675,000 Americans over the next two years.

Churches were closed. Public dance halls were shuttered. No corner of the nation’s capital was spared — not even the White House.

On Friday, President Donald Trump announced that he and first lady Melania Trump have contracted the novel coronavirus, the deadliest pandemic since the 1918 flu. Trump — who has repeatedly played down the risks of the virus and eschewed the masks his own scientists recommend — was diagnosed after a top aide, Hope Hicks, tested positive.

In 1918, Wilson’s personal secretary was among the first in his administration to be sickened. Margaret, his eldest daughter, got it. Secret Service members did, too. Even the White House sheep were not spared.

Also not spared: the president of the United States.

In April 1919, Wilson traveled to the Paris Peace Conference for talks on ending the Great War. Soon after arriving, the president become ill with a fever and violent fits of coughing that left him nearly unable to breathe.

Wilson’s condition deteriorated so quickly that his personal doctor, Cary T. Grayson, thought he had been poisoned.

“But it soon became obvious the diagnosis was simpler, if only marginally more reassuring,” wrote John Barry in “The Great Influenza.”

Wilson was so ill that the talks were nearly derailed. The president could not even sit up in bed.

In a hand-delivered letter to Wilson’s chief of staff back in Washington, Grayson wrote that the night Wilson became ill “was one of the worst through which I have ever passed. I was able to control the spasms of coughing but his condition looked very serious.”

Wilson’s administration worked furiously to keep Wilson’s diagnosis a secret. Grayson told reporters that Wilson had a cold and just needed some rest, blaming the president’s illness on the rainy weather in Paris.

Meanwhile, Wilson’s condition worsened. And he began acting strange.

“Generally predictable in his actions, Wilson began blurting unexpected orders,” A. Scott Berg wrote in his biography of Wilson. “Twice he created a scene over pieces of furniture that had suddenly disappeared,” even though the furniture had not moved. Wilson also thought he was surrounded by spies.

Wilson’s entourage was worried — not just about his illness, but also about the talks falling apart because of what the illness was doing to his behavior.

Barry recounts how in a meeting at Wilson’s bedside, he told negotiators: “Gentlemen, this is not a meeting of the Peace Commission. It is more a Council of War.” Barry described a frightening portrait of a president:

“Colonel Starling of the Secret Service noticed that Wilson ‘lacked his old quickness of grasp, and tired easily.’ He became obsessed with such details as who was using the official automobiles. When Ray Stannard Baker was first allowed to see Wilson again, he trembled at Wilson’s sunken eyes, at this weariness, at his pale and haggard look, like that of a man whose flesh has shrunk away from his face, showing his skull.”

The talks went on, with Wilson relying on deputies before he could return to face-to-face talks. Ultimately, he yielded to several French demands that he had previously said were nonnegotiable. The president fully recovered, only to be stricken by a major stroke a few months later.

In the years since Wilson’s death in 1924, scholars have debated whether he actually suffered a stroke during the conference — not the flu.

Barry opposes those theories. Wilson’s symptoms, which included “high fever, severe coughing, and total prostration,” Barry wrote, “perfectly fit influenza and have no association whatsoever with stroke.”

How did Wilson’s illness affect world civilization? Would the peace terms have been different? Would the war have gone on?

“No one can know what would have happened,” Barry wrote. “One can only know what did happen. Influenza did strike Wilson.”