What is the major contribution to medical science made by Alexander the Great?

Alexander the Great's major contribution to medical science was that he supported the creation of the first medical school. This school, known as the School of Cos, was established in the city of Kos on the island of the same name, and it laid the foundation for the practice of medicine as a scientific discipline. The School of Cos introduced the concept of clinical observation and the systematic study of diseases and their treatments, greatly advancing medical knowledge and practice during that time.