When was Typhus vaccine invented

ZINSSER, Hans (1878–1940), American bacteriologist noted for his work in combating typhus fever, and for a popular book about typhus, Rats, Lice and History (1935). Zinsser was born in New York City and educated in medicine at Columbia University. He was professor of bacteriology at Stanford University (1911), at Columbia University (1913), and at Harvard University Medical School (1923–40).

A pioneer in the science of immunology, Zinsser did extensive research on cholera and bacteriological diseases. He isolated the microorganism that causes one form of typhus, and in 1940, with his associates at Harvard, he devised a method for producing a typhus vaccine in large quantities. His autobiography, As I Remember Him, was published in 1940.