what year was the flu vaccine invented
History and Development of Flu Vaccines. In 1933, researchers discovered that viruses (influenza virus types A, B, and rarely C) cause influenza (flu). Prior to 1933, a bacterium named Haemophilus was thought to cause the flu. In 1938, Jonas Salk and Thomas Francis developed the first vaccine against flu viruses.This first flu vaccine was used to protect the U.S. military forces against the flu during World War II. Dr. Salk used his experience with influenza vaccine to develop an effective polio vaccine in 1952.o live viruses, eggs, or mercury preservatives are used, so this vaccine is live virus-, mercury-, and egg-free. A major change in terminology (naming conventions for influenza vaccines) occurred in the 2014-2015 vaccine year.