In a similar vein, it was hypothesized that the terrible influenza epidemic that hit the world right after WWI was incubated in large part by the discovery of ASPIRIN. - After the war, soldiers returned to their homes carrying the new discovery - the miracle medicine - aspirin. - Theory was that aspirin brought fever down; and fever was what zapped the virus at just the right time to render it harmless. - So, a temperature was our friend.
The Spanish Flu started during WWI, not after it.
Fevers do not kill completely the virus and does not necessarily render it harmless, but supposedly can lower the amounts of virus in a sick person's body, because viruses replicate less efficiently in higher temperatures. Fever is also thought to help immune responses work better but I do not think that mechanism or how it may affect disease transmission is clearly understood.
The 1917-1918 Flu Pandemic that started during WWI, not after, was so virulent and so deadly however, that I doubt that fever reduction by using aspirin would have made much of a difference. For one thing, remember also that influenza is transmittable even during the early stages when a person is only beginning to have symptoms and often before developing a fever. Also the Spanish Flu was unlike most other strains of influenza in that it was most deadly among young adults (aged 20 to 40) as opposed to the very young, the elderly and those with pre-existing illnesses. And those who died from it, many died within days of first showing any symptoms.
http://www.livescience.com/42763-reducing-fever-kills-others.html
http://science.howstuffworks.com/life/cellular-microscopic/question45.htm
However, prolonged high fevers also can very dangerous and kill. One reason is because it causes dehydration. Dehydration can cause dangerous amounts of mucus to build up in the lungs and can lead to kidney failure. And yes, the old “Feed A Cold But Starve A Fever” advise is wrong.
http://www.scientificamerican.com/article/fact-or-fiction-feed-a-cold/
Aspirin is thought to have caused some deaths during the Spanish Flu epidemic but not because it reduced fever but because some people overdosed themselves with way too much aspirin.
Which is why I only take several grams of Vitamin C every 6 hours when I get sick. Helps keep fever from getting much above 102, enhances white blood cell formation, and has useful antihistaminic effects on swollen, drippy mucous membranes.