In England in 1933, Andrewes and his colleagues applied Shope’s methodology to human material and found the human pathogen. It was a filter-passing organism, a virus, like Shope’s swine influenza. In 1938, Thomas Francis and Jonas Salk created a vaccine, growing inactivated virus in chicken eggs; it protected soldiers during World War II and in 1946 was given to civilians. Salk of course later developed the first polio vaccine.
