Progress in Global Surveillance and Response Capacity 10 Years After Severe Acute Respiratory Syndrome

Christopher R. Braden; Scott F. Dowell; Daniel B. Jernigan; James M. Hughes


Emerging Infectious Diseases. 2013;19(6) 

In This Article

Superspreading Events Linked to the Hotel Metropole

Several superspreading events contributed to the dissemination of the virus. Some of the most dramatic examples included those associated with the Hotel Metropole in Hong Kong,[11] the Amoy Gardens apartment complex in Hong Kong,[12] Air China flight 112 from Hong Kong to Beijing,[13] and an acute care hospital in Toronto, Ontario, Canada.[14] The episode at Hotel Metropole that contributed greatly to the initial cross-border spread of the disease was particularly noteworthy.

The cluster of SARS cases at Hotel Metropole in Hong Kong in 2003, the first superspreading event recognized outside mainland China, was responsible for the spread of the epidemic from Guangdong Province to Canada, Vietnam, Singapore, and Hong Kong itself. In addition to the first 13 cases originally associated with the Hotel Metropole,[11] a follow-up cohort study of guests from Canada, Germany, England, and the United States who stayed at the hotel concurrent with the index case-patient, a physician from Guangdong, identified an additional 7 cases that met the probable[2] or confirmed[5] case definition for SARS coronavirus (CoV) infection.[15] All 20 cases were associated with transmission of SARS CoV on the ninth floor of the hotel, where the index case-patient had stayed for 1 night before becoming critically ill and being admitted to a local hospital the next day. Three deaths occurred among hotel guests who had been identified as case-patients, resulting in a case-fatality ratio of 15%. Known secondary SARS cases were associated with at least 13 (42%) of 31 guest rooms on the ninth floor (Figure 1).

Figure 1.

Layout of ninth floor of Hotel Metropole, where superspreading event of severe acute respiratory syndrome (SARS) occurred, Hong Kong, 2003. *2 cases in room; †see (16); ‡case-patient visited room. CoV, coronavirus.

The high rate of infection among guests staying on the ninth floor at the Hotel Metropole is remarkable because they did not have direct contact with the index case-patient. For example, 1 resident of Hong Kong who visited a friend on the ninth floor (but was not a hotel guest) likely acquired his infection during his visit; this person subsequently infected 143 people at Prince of Wales Hospital in Hong Kong.[17] Epidemiologic evidence suggested an environmental route of SARS CoV transmission. Indeed, environmental contamination with SARS CoV RNA was identified on the carpet in front of the index case-patient's room and 3 nearby rooms (and on their door frames but not inside the rooms) and in the air intake vents near the centrally located elevators.[17] Guest rooms had positive air pressure relative to the corridor, and there was no direct flow of air between rooms. The lack of air flow between rooms and the absence of SARS CoV RNA detected inside guest rooms suggest that secondary infections occurred not in guest rooms but in the common areas of the ninth floor, such as the corridor or elevator hall. These areas could have been contaminated through body fluids (e.g., vomitus, expectorated sputum), respiratory droplets, or suspended small-particle aerosols generated by the index case-patient; other guests were then infected by fomites or aerosols while passing through these same areas. Efficient spread of SARS CoV through small-particle aerosols was observed in several superspreading events in health care settings, during an airplane flight, and in an apartment complex.[12–14,16–19] This process of environmental contamination that generated infectious aerosols likely best explains the pattern of disease transmission at the Hotel Metropole.

The compilation of data from multiple superspreading events in the SARS epidemic yields valuable findings that could be relevant for other respiratory infections of pandemic potential. These events underscore the potential for aerosol transmission in non–health care settings and the dramatic role such transmission can play in the global transmission of respiratory diseases.