One hundred and one years ago the American public was riveted by the health of the United States president.

Woodrow Wilson, who earlier that year had contracted what was believed to be a case of the same flu that killed millions across the world, was described on the Oct. 2, 1919, front page of The Spokane Chronicle as experiencing “restlessness.” It would take months before the public learned the 63-year-old had experienced a paralyzing stroke.

That lack of immediate, upfront information about Wilson’s health is a common thread among presidents who have experienced health complications in office, said Margaret O’Mara, a professor of American political history at the University of Washington. It’s a trend that could help explain the anxiety following President Donald Trump’s COVID-19 diagnosis and the effect it could have on the upcoming election.

“I think it has to do with the challenges of the office, and the need for a president to present as strong and healthy,” O’Mara said.

A viral infection arriving during a pandemic that has become the key issue in Trump’s reelection campaign against Joe Biden sets 2020 apart from Wilson’s stroke, or Franklin Delano Roosevelt’s heart disease, or concerns that Ronald Reagan had a cognitive decline in the final years of his presidency, O’Mara said.

“We have a White House that has not sort of proven itself, or is known for being forthcoming, and has been dismissive of public health,” O’Mara said.

Michael Conlin, a professor of early American history at Eastern Washington University, agreed that Trump’s diagnosis – despite it occurring on the anniversary of Wilson’s stroke – is a development in the history of the presidency for which there’s not a clear analog.

“I don’t think there’s any reliable precedent, or similar event,” Conlin said.

The only electoral comparison he could draw was to the election of 1824, when Democratic-Republican candidate William Crawford was known to have suffered a severe stroke a year before ballots were cast. But Crawford finished third in balloting, and when the election was thrown to the House of Representatives, Crawford finished well behind John Quincy Adams and Andrew Jackson.

That election also occurred at a time when the power and influence of the U.S. presidency was far less than what it is today, both O’Mara and Conlin noted. A powerful executive branch, including the authority to launch nuclear strikes, is a relatively new development in the country’s history and raises the stakes of serious illness more than in the 19th and early 20th century.

“Stock markets around the world didn’t wait with bated breath for the health of William Henry Harrison, or Zachary Taylor,” Conlin said, referring to two presidents who died of natural causes in the 19th century.

“Having a presidential disability, or infirmity, is a really high-stakes thing. There’s a lot riding on this,” O’Mara added.

History may also provide a lesson that Trump’s infection could have further-reaching consequences than simply the outcome of the 2020 election. Historians have generally agreed that Wilson contracting the flu in spring 1919 stifled his efforts to push for a treaty ending World War I that was less harsh on Germany. The Treaty of Versailles is largely credited for the later rise of fascism in Europe and the outbreak of World War II.

Trump’s diagnosis, and its effect on foreign and domestic policy in addition to how voters cast their ballots over the next few weeks, could be a similar moment in history, Conlin said.

“It’s possible this could be a similarly momentous moment. As we historians say, a turning point, a pivot, a hinge,” he said. “It’s quite possible that this could be a similar epoch-defining event.”