Hi,
The Lusitania was sunk in 1915 and the US did not enter the war until almost two years after the sinking. The sinking of the Lusitania and the American reaction to that sinking caused the Germans to temporarily halt their policy of unlimited submarine warfare.
Side note: Found the answer with this link :)
https://www.enotes.com/homework-help/what-impact-did-sinking-lusitania-have-what-came-418703
The answer could be that how his family and White House mislead the public about his illness. James Reston comments that journalists do not take the health of candidates seriously and that needs to change.
