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Biosecurity News in Brief
Study Indicates Few Effects from Hong Kong’s Flu-Related School ClosureBy Nidhi Bouri, September 22, 2008 Hong Kong researchers have published the results of a study in the October 2008 online edition of Emerging Infectious Diseases, indicating that a 2-week school closure in Hong Kong during the March 2008 influenza epidemic had little positive effect on the outcome of the epidemic. As reported by Center for Infectious Disease Research & Policy (CIDRAP), after they examined flu surveillance data collected before, during, and after the flu outbreak, the researchers concluded that “the flu season was already waning when officials decided to close the schools.”1 After their review of outpatient consultation data, the research group also concluded that “the 2008 winter flu season was moderately severe compared with the previous 9 years.”1 On March 12, 2008, after 3 children died from what health officials believed to be seasonal flu, Hong Kong’s government closed all primary schools, special schools, day nurseries, and kindergartens for a 2-week period. This was the first school closure in Hong Kong since the 2003 SARS epidemic, which affected approximately 560,000 children.1 According to the study, “routine surveillance data did not detect a large effect from the school closures.”2 The authors also concluded that “the epidemic curves generated from the surveillance data showed a decline in cases that may have naturally concluded without any intervention,” though they noted the difficulty of “making inferences directly from changes in epidemic curves because changes in the epidemic curve may lag behind changes in the underlying transmission dynamics,” as had been shown for SARS.2 The authors also stated that the results should be interpreted with caution, as “influenza might have continued to circulate for a longer period had the school closures not been implemented,” while also acknowledging that in other studies, school closures have seemed to mitigate epidemics.2 The study explains how the data that public officials used to make the decision to close the schools may not have detected that the flu season was moderate and may have been naturally declining.2 Therefore, as the study emphasizes, improving surveillance systems, particularly systems for real-time or near real-time reporting, would allow officials to make more informed decisions. References
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