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 Yu 

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