Published: May 20, 2012
Yu H, et al. “Transmission Dynamics, Border Entry Screening, and School Holidays during the 2009 Influenza A (H1N1) Pandemic, China.EID, May 20, 2012, 18(5):758-766.

Contact:  Neil Ferguson
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Imperial College London

National surveillance data and transmission patterns of 2009 A(H1N1) in China

Pandemic influenza A (H1N1) 2009 virus spread rapidly around the world in 2009. Multiple data sources from surveillance systems and specific investigations were used to characterize the transmission patterns of this virus in China during May-November 2009 and analyze the effectiveness of border entry screening and holiday-related school closures on transmission. In China, age distribution and transmission dynamic characteristics were similar to those in Northern Hemisphere temperate countries. The epidemic was focused in children, with an effective reproduction number of ≈1.2-1.3. The 8 days of national holidays in October reduced the effective reproduction number by 37% (95% credible interval 28%-45%) and increased underreporting by ≈20%-30%. Border entry screening detected at most 37% of international travel-related cases, with most (89%) persons identified as having fever at time of entry. These findings suggest that border entry screening was unlikely to have delayed spread in China by >4 days.

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The Bill and Melinda Gates Foundation (VMI) and the National Institutes of Health Modeling of Infectious Agents Study (MIDAS) provided, in part, funding support for this study.

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