On March 23, 2003, a 74-year-old immunocompromised man was transferred to our ICU from a hospital where the original cluster of Toronto's SARS cases occurred. The patient originally had signs and symptoms consistent with a presumptive diagnosis of community-acquired pneumonia. Before transfer, SARS was excluded from the differential diagnosis because the patient had not traveled, had never left the emergency department of the referring hospital, and had only had a single recent outpatient visit to an area of the original hospital in which SARS had not been identified. Upon arrival in our ICU, the patient was placed in precautions for methicillin-resistant Staphylococcus aureus (MRSA) pending admission screening results. Therapy with broad-spectrum antimicrobial drugs was initiated. Humidified high-flow oxygen was administered for the first 5 h, noninvasive positive pressure ventilation by oronasal mask for the next 18.25 h, and invasive mechanical ventilation for the subsequent time (7.5 h). Endotracheal intubation required fiber-optic placement. That the extent of the outbreak at the referring institution was larger than originally appreciated became apparent at this time; therefore, the patient was transferred to another facility for placement in negative pressure isolation for possible exposure to SARS. Subsequently, his family members became ill, and the SARS-associated coronavirus was identified in the patient's respiratory secretions (polymerase chain reaction testing of bronchoalveolar lavage confirmed the diagnosis of SARS).
Once the risk for SARS was identified, all patients in the ICU were considered to have been potentially exposed. To prevent spread of SARS, we closed the ICU to admissions and discharges and implemented strict respiratory and contact precautions for all remaining patients. We quarantined 69 healthcare workers who were considered to be at high risk for developing SARS. On the basis of our understanding of disease transmission, we arbitrarily decided that persons at high risk included anyone who had entered the index patient's room or who had been in the ICU for >4 hours during the patient's 30.75-h stay.