The first written descriptions of the concept of immunity may have been made by the Athenian Thucydides who, in 430 BC, described that when the plague hit Athens: "the sick and the dying were tended by the pitying care of those who had recovered, because they knew the course of the disease and were themselves free from apprehensions.
A primeira descrición escrita do concepto de inmunidade puido ser a que fixo o ateniense Tucídides que, no ano 430 a. C., describiu que cando a peste afectou a Atenas “os doentes e os moribundos estiveron coidados pola atención compasiva daqueles que se recuperaran, porque sabían o tratamento da doenza e estaban eles mesmos libres de temor.