They're trying to make it where you're allergic to it, which is what killed most of the people in the Spanish flu was they were allergic to the virus, not that it was actually replicating and killing them. They had an autoimmune response.

If you know your history, you also know that 1918 happens to be at the tail end of World War I. What you might not remember so easily is that Spain was neutral in World War I, which meant that they weren't living in the same wartime restrictions as most of the other allied or central power countries were. Due to the need to keep morale high, almost every country that was involved in World War I had highly censored news publication rules, and they actively suppressed reporting about the flu. This was not a consideration for the Spanish media, who were relatively free to report on the reality of the outbreaks going on. Beginning in May 1918, they were reporting more candidly than anyone else about what was actually happening, which made it appear that they were the source of the outbreak, which probably wasn't true. No one actually knows definitively where the flu of 1918 came from, but there are a number of theories, none of which are Spain.