Dr. McGeer completed an undergraduate and master's degree in biochemistry, then her medical degree at the University of Toronto. She specialized in internal medicine and infectious diseases followed by a fellowship in hospital epidemiology at Yale New Haven Hospital.
She returned to Mount Sinai Hospital in 1989 as microbiologist and director of infection control. Her major research interests are in the prevention of infection in hospitals and nursing homes, and the use of surveillance to advance the prevention, diagnosis and treatment of infectious diseases. She is the principal investigator of the Toronto Invasive Bacterial Diseases Network and the Ontario Group A Streptococcal Study, two collaborative surveillance networks studying the epidemiology of severe community-acquired infections.
Dr. McGeer is a Professor in the Departments of Laboratory Medicine and Pathobiology and Public Health Sciences at the University of Toronto. In addition to her position as director of infection control at Mount Sinai Hospital, Dr. McGeer is an infection control consultant to The Scarborough Hospital and The Baycrest Centre for Geriatric Care. She currently serves on Canada's National Advisory Committee on Immunization and on the infection control subcommittee of the Ontario Provincial Infectious Diseases Advisory Committee, and is a member of several local, provincial and national pandemic influenza committees. She is an expert reviewer for many research funding agencies including the Canadian Institute of Health Research and US National Institutes of Health, and has served on the editorial boards of several journals, including the Canadian Medical Association Journal, and Infection Control and Hospital Epidemiology.