Territory-wide SARS Seroprevalence Study Suggests
¡@¡@"Keep Hong Kong SARS-free" was the first population-based study to determine the prevalence of asymptomatic SARS-associated coronavirus (SARS-CoV) infection in Hong Kong. 50,000 randomly selected households were invited to participate in the project between September and October 2003. ¡@¡@To prevent Hong Kong from further attacks by SARS and other emerging infectious diseases unprepared, the Faculty of Medicine of The Chinese University of Hong Kong established CEID and immediately launched its first population-based serological survey last year to: 1) determine the prevalence of antibody to SARS-coronavirus in the general population of Hong Kong, and to 2) examine the risk factors predisposing to asymptomatic SARS infection. ¡@¡@Blood samples from 12,000 Hong Kong citizens were collected and screened for the presence of the SARS-CoV antibody using enzyme-linked immunosorbent assay (ELISA). Positive samples underwent immunoflourescence assay (IFA) and Western Blot for confirmation. ¡@¡@Fifty-three subjects had a positive test on initial ELISA screening; seven of them were confirmed as true positives. Among these seven positive cases, only one had asymptomatic infection. The prevalence of asymptomatic SARS-CoV infection in this study was 0.009% (95% confidence interval, 0.0002% - 0.06%). It is thus estimated that there are only about 630 asymptomatic SARS cases in Hong Kong. Hence, asymptomatic SARS-CoV infection is very rare in Hong Kong. The study suggests most Hong Kong citizens had not been exposed to the virus. Importantly, the result implies that there is no significant human reservoir for SARS-CoV infection in Hong Kong. ¡@¡@"Keep Hong Kong SARS-free" was a research project funded by the Research Grants Council Earmarked Research Grant (2003-2004). |