In 1918 there was an outbreak of bubonic plague in northern Shanxi that lasted for two months and killed 2,664 people. Yan's interactions with the Western medical personnel he met with to discuss how to suppress the epidemic inspired him to modernize and improve Shanxi's medical infrastructure which he began by funding the Research Society for the Advancement of Chinese Medicine, based in Taiyuan, in 1921. Highly unusual in China at the time, the school had a four-year curriculum and included courses in both Chinese and Western Medicine. The main skills that Yan hoped physicians trained at the school would learn were: a standardized system of diagnosis; sanitary science, including bacteriology; surgical skills, including obstetrics; and, the use of diagnostic instruments. Yan hoped that his support of the school would eventually lead to increased revenues in the domestic and international trade of Chinese drugs, improved public health, and improved public education. Yan's promotion of a modern curriculum and infrastructure of Chinese medicine achieved limited success, but much of the teaching and publication that this school of medicine produced was limited to the area around Taiyuan: by 1949 three of the seven government-run hospitals were in the city. In 1934 the province produced a ten-year-plan that envisaged employing a hygiene worker in every village, but the Japanese invasion in 1937 and the subsequent civil war made it impossible to carry these plans out. Yan's generous support for the Research Association for the Improvement of Chinese Medicine generated a body of teaching and publication in modern Chinese medicine that became one of the foundations of the national institution of modern traditional Chinese medicine that was adopted in the 1950s.