SARS transmission and hospital containment

Abstract

An outbreak of severe acute respiratory syndrome (SARS) was detected in Singapore at the beginning of March 2003. The outbreak, initiated by a traveler to Hong Kong in late February 2003, led to sequential spread of SARS to three major acute care hospitals in Singapore. The critical factor in containing this outbreak was early detection and complete assessment of movements and follow-up of patients, healthcare workers, and visitors who were contacts. Visitor records were important in helping identify exposed persons who could carry the infection into the community. In the three hospital outbreaks, three different containment strategies were used to contain spread of infection: closing an entire hospital, removing all potentially infected persons to a dedicated SARS hospital, and managing exposed persons in place. On the basis of this experience, if a nosocomial outbreak is detected late, a hospital may need to be closed in order to contain spread of the disease. Outbreaks detected early can be managed by either removing all exposed persons to a designated location or isolating and managing them in place.

Figure 1

Severe acute respiratory syndrome case-patients infected at three major hospitals, Singapore, February–April 2003. The chart depicts the overall epidemic in each hospital, includes case-patients infected outside the hospital but whose disease origin was linked back to one of the three hospital outbreaks. In Tan Tock Seng Hospital (TTSH), the last case of intrahospital transmission was on April 12. In Singapore General Hospital (SGH), the last case of intrahospital transmission was on April 15. In National University Hospital (NUH), the last case of intrahospital transmission was on April 25. Arrows indicate dates of onsets of the three index cases for each hospital outbreak. Dotted arrow indicates date when full infection control measures (Figure 2) were implemented in TTSH.

Figure 2

Timeline of events in the outbreak of SARS in the three acute hospitals, Singapore March–May 2003. SARS, severe acute respiratory syndrome; TTSH, Tan Tock Seng Hospital; ED, emergency department; PPE, personal protective equipment (defined as a test-fitted N95 mask, gowns, and gloves; goggles if dealing with suspicious cases; powered air purified respirators for high-risk procedures such as intubation); ICU, intensive care unit; high-risk area defined as ED, ICU, isolation wards; SGH, Singapore General Hospital; NUH, National University Hospital; HCW, healthcare worker. Staff found to have a temperature >37.5°C were given medical leave for 3 days with a review on the third day.