Max Theiler working on yellow fever. In 1926, they disproved Hideyo Noguchi's hypothesis that yellow fever was caused by the bacterium "Leptospira icteroides." In 1928, the year after the disease was identified conclusively as a virus, they showed that the African and South American viruses are immunologically identical. (This followed Adrian Stokes' inducing yellow fever in rhesus macaques from India). In the course of this research, Theiler contracted yellow fever, but survived and developed immunity. In 1930, Theiler moved to the Rockefeller Foundation in New York, where he later became director of the Virus Laboratory. He was professor of epidemiology and public
Vaccine vaccine is designed to immunize against a single antigen or single microorganism. A multivalent or polyvalent vaccine is designed to immunize against two or more strains of the same microorganism, or against two or more microorganisms. The valency of a multivalent vaccine may be denoted with a Greek or Latin prefix (e.g., "tetravalent" or "quadrivalent"). In certain cases, a monovalent vaccine may be preferable for rapidly developing a strong immune response. Also known as heterologous or "Jennerian" vaccines, these are vaccines that are pathogens of other animals that either do not cause disease or cause mild disease in the organism