430 BCE – Thucydides observes that individuals who recovered from the plague in Athens did not get reinfected, indicating early recognition of acquired immunity.
1000 CE – Chinese and Indian physicians use variolation (inoculation with smallpox material) to protect against smallpox, marking the first recorded form of immunization.
1796 – Edward Jenner demonstrates that cowpox exposure provides protection against smallpox, founding the concept of vaccination.
1800 – Vaccination becomes widely accepted in Europe following Jenner’s work, replacing traditional variolation.
1880 – Louis Pasteur develops the first laboratory-produced vaccines (for chicken cholera and anthrax), introducing the principle of attenuated vaccines.
1885 – Pasteur successfully uses a rabies vaccine on a human, marking the first therapeutic use of vaccination.
1890 – Emil von Behring and Shibasaburo Kitasato discover antitoxins and develop serum therapy for diphtheria and tetanus, founding passive immunization.
1891 – Paul Ehrlich proposes the “side-chain theory” to explain how antibodies bind to antigens, laying the groundwork for immunochemistry.
1901 – Emil von Behring is awarded the first Nobel Prize in Physiology or Medicine for serum therapy.
1908 – Elie Metchnikoff and Paul Ehrlich share the Nobel Prize for discoveries in cellular (phagocytosis) and humoral (antibody-based) immunity.
1930s – Discovery of blood groups (ABO system by Karl Landsteiner) and development of transfusion immunology.
1942 – Development of the first effective vaccines for typhus and influenza during World War II.
1957 – Macfarlane Burnet and Frank Fenner propose the clonal selection theory, explaining how immune cells recognize and remember antigens.
1972 – Rodney Porter and Gerald Edelman win the Nobel Prize for determining the structure of antibodies.
