It happened because medicine was poverty stricken till Rockefeller came along Rockefeller Standard Oil Origin of Big Pharma & ALL Medical Schools and & Text books Rockefeller was infamous for his organised crime style of management and sponsoring medical schools served to partly rehabilitate his blackened public reputation
Well researched and referenced piece written By Dr. Gary G. Kohls, MD "The truth about the Spanish influenza" It Started with the Rockefeller Institute’s Crude Bacterial Meningitis Vaccination Experiment on US Troops. The 1918-19 bacterial vaccine experiment may have killed 50-100 million people
https://fort-russ.com/2020/05/did-psychopath-rockefeller-create-the-spanish-flu-pandemic-of-1918/