Who recognized that individuals who recovered from the plague could care for the sick without getting ill again?

Thucydides is recognized for observing that individuals who had recovered from the plague were able to care for those who were sick without falling ill themselves. This observation highlights an early understanding of immunity, suggesting that prior exposure to a disease can provide protection against future infections. Thucydides, a historian of the Athenian plague, documented this phenomenon in his writings, which reflected an early glimpse into the concept of acquired immunity based on previous illness.

Hippocrates, known as the father of medicine, laid the groundwork for clinical observation but did not specifically document immunity in relation to plague. Edward Jenner is famous for developing the smallpox vaccine, marking a significant advancement in immunology but well after Thucydides’ time and focusing on vaccination rather than natural immunity. Louis Pasteur contributed significantly to the germ theory of disease and developed vaccines for several diseases, but like Jenner, he did not explore the concept of natural immunity as observed in the context of the plague. Thucydides' insights are foundational to the understanding of the immune response, making his recognition a critical element in the history of medicine and immunology.