We have learned that the Spanish flu was an influenza that spread at the end of and after the First World War, killing millions of people worldwide. What many may not know is that the majority, over 95%, died from bacterial pneumonia and not influenza.
Facts point to the U.S. and a military base as the origin. From January to June 1918, a vaccine against bacterial meningitis was developed by the Rockefeller Institute for Medical Research in New York, tested on soldiers at Fort Riley in Kansas. The first cases of bacterial pneumonia then occurred there. The soldiers were later sent to fight in Europe, and the serum from the Rockefeller Institute spread to countries in Europe.
palbergstrom.com, Was the Spanish flu caused by a vaccine developed in the USA?