Wednesday, July 3, 2013

CDC - Protection by Face Masks against Influenza A(H1N1)pdm09 Virus on Trans-Pacific Passenger Aircraft, 2009

Volume 19, Number 9—September 2013

Research

Lijie Zhang1, Zhibin Peng1, Jianming Ou1, Guang Zeng1, Robert E. Fontaine, Mingbin Liu, Fuqiang Cui, Rongtao Hong, Hang Zhou, Yang Huai, Shuk-Kwan Chuang, Yiu-Hong Leung, Yunxia Feng, Yuan Luo, Tao Shen, Bao-Ping Zhu, Marc-Alain Widdowson, and Hongjie YuComments to Author 
Author affiliations: Chinese Center for Disease Control and Prevention, Beijing, China (L. Zhang, Z. Peng, G. Zeng, M. Liu, F. Cui, H. Zhou, Y. Feng, Y. Luo, T. Shen, B.-P. Zhu, H. Yu); Fujian Center for Disease Control and Prevention, Fuzhou, China (J. Ou, R. Hong); Nanchang Center for Disease Control and Prevention, Nanchang, China (M. Liu); Centers for Disease Control and Prevention, Atlanta, Georgia, USA (R. E. Fontaine, M.-A. Widdowson); China–US Collaborative Program on Emerging and Re-emerging Infectious Diseases, Beijing (Y. Huai); Hong Kong Department of Health, Hong Kong, China (S.-K. Chuang, Y.-H. Leung)

Abstract

In response to several influenza A(H1N1)pdm09 infections that developed in passengers after they traveled on the same 2 flights from New York, New York, USA, to Hong Kong, China, to Fuzhou, China, we assessed transmission of influenza A(H1N1)pdm09 virus on these flights. We defined a case of infection as onset of fever and respiratory symptoms and detection of virus by PCR in a passenger or crew member of either flight. Illness developed only in passengers who traveled on the New York to Hong Kong flight. We compared exposures of 9 case-passengers with those of 32 asymptomatic control-passengers. None of the 9 case-passengers, compared with 47% (15/32) of control-passengers, wore a face mask for the entire flight (odds ratio 0, 95% CI 0–0.71). The source case-passenger was not identified. Wearing a face mask was a protective factor against influenza infection. We recommend a more comprehensive intervention study to accurately estimate this effect.

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Discussion:
Excerpt:
In summary, this outbreak probably resulted from a common source exposure to influenza A(H1N1)pdm09 virus on the New York to Hong Kong flight. Wearing a face mask was associated with a decreased risk for influenza acquisition during this long-duration flight. Border entry screening did not detect case-passengers during the influenza incubation period. We recommend a more comprehensive intervention study to accurately estimate the protective effect of face masks for preventing influenza virus transmission on long-distance flights.

http://wwwnc.cdc.gov/eid/article/19/9/12-1765_article.htm 

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