Doctors gave out elixirs and vaccinated people against the flu, but to no avail. Crosby wondered about those flu vaccines. What was in them when no one knew what was causing the flu? He interviewed a doctor who had helped produce flu vaccines in 1918. The doctor, Crosby said, told him that the vaccines were just a soup made of blood and mucus of flu patients that had been filtered to get rid of large cells and debris. When they injected it into people’s arms their arms became horribly sore. “So they thought it really worked.”
