In the late 1800s and early 1900s, intense debates in immunology centered on whether cell-mediated or humoral immunity was the primary defense against pathogens. German physician Paul Ehrlich spearheaded humoral immunity theories, while Russian immunologist Elie Metchnikoff championed cell-mediated immunity. Jules Bordet's research bridged the gap between the theories, leading to a comprehensive understanding of the immune system. These debates furthered the development of vaccines, such as the BCG vaccine for tuberculosis.

The history of immunology spans centuries, beginning with variolation practices in Ancient China. Edward Jenner furthered this field by creating the smallpox vaccine, while Louis Pasteur's germ theory significantly enhanced the understanding of infectious diseases. Paul Ehrlich's side-chain theory and the discovery of antibodies facilitated the understanding of the immune system's defense mechanisms. The 20th and 21st centuries saw immunology advancements through the discovery of the immune system's memory and complex immune response components, contributing to vaccine development and immunotherapies.

Infectious diseases have greatly impacted historical events, often changing their outcomes. Widespread diseases during wars, like the Napoleonic Wars and World War I, led to more deaths than actual combat. In the era of slavery and colonialism, Europeans inadvertently spread diseases among indigenous populations, causing devastation that facilitated colonial dominance. In modern times, the HIV/AIDS pandemic has notably influenced socio-political situations in sub-Saharan Africa.