SARS Epidemiologic Summaries:
April 26, 2003

SARS Among Ontario Health Care Workers

Transmission of SARS in the Greater Toronto Area (GTA) is believed to have begun with a travel-related index case in February 2003. Her family contacts, after becoming ill with symptoms compatible with SARS, were treated at a hospital within the GTA and subsequently transmitted the illness to hospital workers and other patients at that hospital. More than 100 hospital workers at three GTA hospitals have since become ill. Initial descriptive epidemiology suggests that transmission occurred in association with the care of patients who were not diagnosed with SARS and were not in isolation precautions, as well as ill family members visiting in hospital.

Disease control strategies included implementation of strict infection control precautions in institutional settings, isolation of cases and symptomatic contacts, as well as quarantining asymptomatic close contacts. Initially, SARS cases were isolated in hospital in negative pressure rooms. However, by early April there was a critical shortage of standard airborne isolation beds within the GTA. In response, SARS negative pressure units were created within some GTA hospitals to increase capacity to care for SARS patients in controlled circumstances.

Since implementation of these control strategies, transmission of SARS to hospital workers has decreased substantially. However, transmission has continued to occur in both high and low risk hospital settings within the GTA despite these measures. High risk procedures have been identified which include intubation, suction, nebulized aerosol therapy, and positive pressure non-invasive ventilation. Transmission of SARS to hospital staff during difficult intubations of SARS patients has occurred in 3 different hospitals. In two, undiagnosed patients were identified as the source of transmission for 7 hospital staff. Although infection control precautions were in place, compliance may not have been complete. In the third, a SARS patient was identified as the source of infection for 7 hospital staff; an additional 6 remain under investigation. Although staff were reportedly compliant with infection control precautions, one break in technique in one caregiver was identified (a face shield was accidentally dislodged). Transmission of SARS to 10-11 hospital staff has also been identified in lower risk settings. Affected staff include physicians, nurses, and service assistants (eg porter/housekeeper) working in 4 different low-risk SARS units and one community hospital. Initial investigation suggests that transmission has occurred while staff were wearing required personal protective equipment and following all recommended infection control precautions.

In response to the continued transmission of SARS to hospital workers, Health Canada is leading an urgent investigation in collaboration with the Centers for Disease Control and Prevention (CDC), the Province of Ontario, and Toronto Public Health. The investigation will include descriptive epidemiology, case control studies, air ventilation studies, as well as surface contamination studies. In addition, an infection control directive specifically for SARS Units is being developed.