John M. Barry is the author of “The Great Influenza: The Story of the Deadliest Pandemic in History” and is a professor at the Tulane University School of Public Health and Tropical Medicine.

Once before a president has been infected by a pandemic virus, and the precedent is both similar and concerning.

In March 1919, the Journal of the American Medical Association reported that in Paris “the epidemic of influenza which had declined has broken out anew in a most disquieting manner.” President Woodrow Wilson was there then negotiating the peace treaty to end World War I. Several members of the American delegation got influenza, and, like covid-19, influenza can be transmitted before symptoms appear.

On Thursday, April 3, Wilson suddenly fell ill. White House physician Cary Grayson noted he was seized by “violent paroxysms of coughing, which were so severe and frequent that it interfered with his breathing,” followed by such other symptoms as high fever. Grayson tried to keep the illness secret, but word leaked out that Wilson was sick, and Grayson lied, insisting Wilson simply had a bad cold. Afraid of another leak, Grayson wrote a note to be hand-delivered to Wilson’s chief of staff which said, “That night 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.”

Today, as coronavirus cases are beginning to surge again, President Trump has been infected and we have a White House less than forthright about his condition. In fairness, other administrations have also hidden the truth about a president’s health, but more concerning than lack of candor are the potential effects of the virus. Like the 1918 virus, SARS-CoV-2 impacts virtually every organ in the body, including the brain. Most worrisome are cardiovascular and neurological impacts.

For covid-19, cardiovascular complications including stroke are so common that some experts consider this, and not the lung, the primary problem. And according to a study in Annals of Neurology, 25 percent of patients have some neurological dysfunction, and 7 percent have “impaired consciousness.” Another study in Clinical Neurology and Neurosurgery found 36.4 percent of patients to have neurological symptoms.

In 1918, it was much the same. Autopsies found the heart muscle itself often “relaxed and flabby, offering a strong contrast to the firm, contracted left ventricle nearly always present in post-mortem in bodies of patients dying from lobar pneumonia.” And the single most comprehensive study of the 1918 pandemic concluded — a conclusion shared by every study — “The effect of the influenza virus on the nervous system is hardly second to its effect on the respiratory tract. … From the delirium accompanying many acute attacks to the psychoses that develop as ‘post-influenzal’ manifestations, there is no doubt that the neuropsychiatric effects of influenza are profound.”

For Wilson, and the world, the effects were indeed profound. He became paranoid, convinced he was being spied on. Said one aide, “Something queer was happening in his mind. One thing was certain: he was never the same after this.” Another worried that “he could not remember without an effort what” had happened just a few hours earlier. Herbert Hoover believed Wilson’s mind lost “resiliency” and its ability to reason clearly “in coming to conclusions.”

Nonetheless, after five days in bed and too ill to go out, Wilson insisted on rejoining the peace negotiations. British and French Prime Ministers David Lloyd George and Georges Clemenceau — whose nickname was “the tiger” — came to his room. They too found a different man. Lloyd George commented on Wilson’s “nervous and spiritual breakdown in the middle of the Conference.”

Nothing in Wilson’s prior history suggests he would compromise on any principle, and before his illness, he had insisted upon “peace without victory” and supporting self-determination around the world.

But over the next few days, he gave way on almost every point to Clemenceau and agreed to a peace deal that punished Germany and preserved other nations’ imperial ambitions. John Maynard Keynes called Wilson “the greatest fraud on earth.” A Wilson aide resigned in a blistering letter, saying, “Our government has consented now to deliver the suffering peoples of the world to new oppressions, subjections, and dismemberments—a new century of war.”

He was right. Historians agree that the treaty contributed significantly to the rise of Adolf Hitler and the start of World War II. A few months later, Wilson’s influenza attack very likely contributed to his debilitating stroke.

Today, the case mortality for a 65 to 74-year-old man — Trump is 74 — is 3.1 percent and somewhat higher for those who required oxygen, as he did, so the odds of recovery are strongly in his favor, especially given his immediate treatment with remdesivir and experimental monoclonal antibodies, and now dexamethasone. But recovery may leave him not only fatigued for an extended time but also with an increased chance of stroke or neurological impacts.

In 1918, Grayson lied. Now more than ever, White House doctors must tell the truth. Their first efforts only sowed confusion. Only complete transparency concerning Trump’s health can cure this problem.

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