Hong Kong was the hardest-hit area during the worldwide epidemic with the highest incidence rate and a high fatality rate. In 2003, Hong Kong had 1,755 SARS cases and 299 deaths in a
population of 6.7 million.
A recent study explains the large community outbreak of SARS in Hong Kong. It seems the air may be to blame. Investigators say, for future prevention and control, health care professionals must take the potential for airborne spread of the virus into consideration.
Researchers examined the initial 187 cases of Severe Acute Respiratory Syndrome in China. They found residents on middle and upper floors of the building in which 99 SARS patients lived were at a significantly higher risk than residents on lower floors. This finding is consistent with the rising of contaminated warm air in the air shaft generated from a middle-level apartment unit in that building. Investigators say the contaminated air at the top of the air shaft was then carried toward the other buildings by a northeasterly wind. All but five of the initial patients lived in the seven buildings of the complex.
Management and security staff of the complex who worked on the ground floor in each building would probably have had frequent person-to-person contact with residents, but they were not affected by the virus. Coupled with the finding of much lower concentrations of the virus in respiratory secretions than in urine and stool, researchers conclude the spread was not initiated by respiratory means but by virus-laden aerosols spread through dried up seals in a bathroom and passed on by an exhaust fan.