The Immune system protects itself from infections

Scientists learned more about how the body's immune system protects itself from infections, resulting in new tests for diagnosing infectious diseases and new vaccines to prevent them.
The Wasserman blood test for syphilis was developed in 1906 and the tuberculin skin test for tuberculosis appeared in 1908.
By the 1930s new techniques for growing viruses in the laboratory led to vaccines against viral diseases.
These included a yellow fever vaccine in the late 1930s and the first effective influenza vaccine in the 1940s. The American physician Jonas E. Salk developed a polio vaccine in 1954.
Later virologist Albert B. Sabin developed a safer oral polio vaccine, which was in wide use by the 1960s.
Later came vaccines for other childhood diseases, including measles, German measles, mumps, and chicken pox.