What method did the Chinese and Turks utilize in the fifteenth century to induce immunity?

The correct method used by the Chinese and Turks in the fifteenth century to induce immunity is inoculation with dried crusts from smallpox. This historical practice involved taking material from the sores or crusts of individuals who had recovered from smallpox and then introducing this material into the skin of a healthy person. This method, known as variolation, was designed to provide immunity against smallpox without causing the full-blown disease.

Variolation was a critical advancement in the early days of immunology, as it laid the groundwork for the development of modern vaccines. By deliberately exposing individuals to a less virulent form of the disease, people could develop immunity that would protect them from future infections. This practice showcased an early understanding of how the immune system could be trained to recognize and respond to specific pathogens.

While vaccination with live viruses is a method used in modern immunization practices, it was not the technique utilized during the fifteenth century. Blood transfusions and antibiotic treatment are also modern medical practices that did not exist in that historical context for inducing immunity against diseases such as smallpox.