The comparison is between the last three years and 1915-1918, but the Spanish flu was just getting going in 1918.
EDIT: folks just arriving, the HN title has changed since I commented. It previously said "worst trend since Spanish flu," or something.
> There is no requirement to post the article headline as-is on HN.
There is. From the guidelines:
> Otherwise [i.e. not excessive clickbait] please use the original title, unless it is misleading or linkbait; don't editorialize.
It's a title, not a series of facts
https://news.ycombinator.com/newsguidelines.html
Submitters: Cherry-picking a detail from an article is editorializing, so please don't do that. If you want to say what you think is important about the topic, please do so in a comment, where your view is on a level playing field with everyone else's.
https://hn.algolia.com/?sort=byDate&dateRange=all&type=comme...
It was not Spanish. It's origins come from the battlefields of WWI.