The 1918 pandemic was even worse than COVID. And it infected Woodrow Wilson when he was in Paris for WWI negotiations.
Meilan Solly at The Smithsonian:
Wilson’s bout of influenza “weaken[ed] him physically … at the most crucial point of negotiations,” writes Barry in The Great Influenza. As Steve Coll explained for the New Yorker earlier this year, the president had originally argued that the Allies “should go easy” on Germany to facilitate the success of his pet project, the League of Nations. But French Prime Minister Georges Clemenceau, whose country had endured much devastation during the four-year conflict, wanted to take a tougher stance; days after coming down with the flu, an exhausted Wilson conceded to the other world leaders’ demands, setting the stage for what Coll describes as “a settlement so harsh and onerous to Germans that it became a provocative cause of revived German nationalism … and, eventually, a rallying cause of Adolf Hitler.”
Whether Wilson would have pushed harder for more equitable terms if he hadn’t come down with the flu is, of course, impossible to discern. According to Barry, the illness certainly drained his stamina and impeded his concentration, in addition to affecting “his mind in other, deeper ways.”