In the late 19th century, outbreaks of infectious diseases such as diphtheria and scarlet fever created a great demand in Toronto for medical staff. Dr. Norman Allen, Toronto's Medical Officer of Health, wrote to the Sisters of St. Joseph in 1891, asking for help. The sisters sent six nuns to care for the ill at the Isolation Hospital. By 1894, the hospital had established a training school for nurses.
In 1922, Riverdale Isolation Hospital became the University of Toronto's teaching centre for the treatment of communicable diseases. It was supervised by Dr. Beverly Hannah. A nurses' residence was soon built to support this important program. In 1945 the hospital's South Building was renovated and renamed the Hannah Building.
Between 1910 and 1929, Chief Medical Officer Dr. Charles Hastings brought about many health reforms in Toronto. He helped reduce the spread of disease by creating policy for public vaccination. He spearheaded legislation to pasteurize milk and chlorinate drinking water. It was Dr. Hastings who helped secure state-of-the-art steam laundry facilities for Riverdale Isolation Hospital, which named a ward in his honour in 1927.
These doctors and nurses, along with many others, have played a significant role in the evolution of healthcare services at this site.