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Risk Factors for Influenza A(H1N1)pdm09 among Students, Beijing, China - Vol. 19 No. 2 - February 2013 - Emerging Infectious Disease journal - CDC

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Risk Factors for Influenza A(H1N1)pdm09 among Students, Beijing, China - Vol. 19 No. 2 - February 2013 - Emerging Infectious Disease journal - CDC

Georges de La Tour (1593‒1652) La Femme à la puce (The Flea Catcher) (1638) Oil on canvas (90 cm × 120 cm) Musée Lorrain, Nancy. Photo P. Mignot

Risk Factors for Influenza A(H1N1)pdm09 among Students, Beijing, China

The Study

Conclusions

Acknowledgment

References

Table 1

Table 2

Technical Appendix [108 KB - 4 pages]

Suggested Citation

Yang Zheng¹, Wei Duan¹, Peng Yang, Yi Zhang, Xiaoli Wang, Li Zhang, Surabhi S. Liyanage, and Quanyi Wang

Author affiliations: Author affiliations: Beijing Center for Disease Control and Prevention, Beijing, People’s Republic of China (Y. Zheng, W. Duan, P. Yang, Y. Zhang, X. Wang, L. Zhang, Q. Wang); University of New South Wales, Sydney, New South Wales, Australia (S.S. Liyanage)

Abstract

To identify risk factors associated with influenza A(H1N1)pdm09 among students in Beijing, China, we conducted a case–control study. Participants (304 case-patients and 608 controls, age range 6–19 years) were interviewed by using a standardized questionnaire. We found that in addition to vaccination, nonpharmaceutical interventions appeared to be protective.

Influenza A(H1N1)pdm09 virus first emerged in Mexico and southern California, USA, in early April 2009 and rapidly spread worldwide (1). The mode of transmission of this novel virus was similar to that of other influenza viruses. Notably, the virus disproportionately affected children and young adults (2). Therefore, further research was required to understand etiologic factors associated with spread of influenza A(H1N1)pdm09 among school-age children to limit transmission within schools and in the community. We conducted a case–control study to identify risk factors associated with influenza A(H1N1)pdm09 among students in Beijing, China.

The Study

Beijing is one of the largest cities in China and has 18 districts and a population of >20 million persons. Although there is considerable variation in district size and a greater population density in urban areas, health care is accessible for residents in all districts. During the pandemic period, the Notifiable Disease Surveillance System (NDSS) was established in Beijing. Fifty-five collaborating laboratories covering all hospitals were authorized to conduct confirmation testing for influenza A(H1N1)pdm09 virus (3). All confirmed cases were reported through the NDSS.
Case-patients were students for whom diagnosis was confirmed during October 1, 2009–January 31, 2010. Stratified sampling was used to recruit case-patients through the NDSS. We randomly selected 3 urban and 3 rural districts from the 18 districts and listed all case-patients <18 years of age. We aimed to randomly select 50 patients from each district.