Facemasks and Hand Hygiene to Prevent Influenza Transmission in Households

A Cluster Randomized Trial

  1. Benjamin J. Cowling, BSc, PhD;
  2. Kwok-Hung Chan, BSc, PhD;
  3. Vicky J. Fang, BSc, MPhil;
  4. Calvin K.Y. Cheng, BSc, MMedSci;
  5. Rita O.P. Fung, BNS;
  6. Winnie Wai, BNS;
  7. Joey Sin, BNS;
  8. Wing Hong Seto, MBBS;
  9. Raymond Yung, MBBS, MPH;
  10. Daniel W.S. Chu, MBBS;
  11. Billy C.F. Chiu, MBBS;
  12. Paco W.Y. Lee, MBBS;
  13. Ming Chi Chiu, MBBS;
  14. Hoi Che Lee, MBBS;
  15. Timothy M. Uyeki, MD, MPH;
  16. Peter M. Houck, MD;
  17. J. S. Malik Peiris, MBBS, DPhil; and
  18. Gabriel M. Leung, MD, MPH
  1. From School of Public Health and University of Hong Kong; Hospital Authority and Centre for Health Protection, Department of Health, Government of the Hong Kong SAR; Hong Kong Sanatorium and Hospital; St Paul's Hospital; St Teresa's Hospital; and Hong Kong Baptist Hospital, Hong Kong; National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; and Seattle Quarantine Station, Division of Global Migration and Quarantine, Centers for Disease Control and Prevention and National Center for Preparedness, Detection and Control of Infectious Diseases, Seattle, Washington.

    Abstract

    Background: Few data are available about the effectiveness of nonpharmaceutical interventions for preventing influenza virus transmission.

    Objective: To investigate whether hand hygiene and use of facemasks prevents household transmission of influenza.

    Design: Cluster randomized, controlled trial. Randomization was computer generated; allocation was concealed from treating physicians and clinics and implemented by study nurses at the time of the initial household visit. Participants and personnel administering the interventions were not blinded to group assignment. (ClinicalTrials.gov registration number: NCT00425893)

    Setting: Households in Hong Kong.

    Patients: 407 people presenting to outpatient clinics with influenza-like illness who were positive for influenza A or B virus by rapid testing (index patients) and 794 household members (contacts) in 259 households.

    Intervention: Lifestyle education (control) (134 households), hand hygiene (136 households), or surgical facemasks plus hand hygiene (137 households) for all household members.

    Measurements: Influenza virus infection in contacts, as confirmed by reverse-transcription polymerase chain reaction (RT-PCR) or diagnosed clinically after 7 days.

    Results: Sixty (8%) contacts in the 259 households had RT-PCR–confirmed influenza virus infection in the 7 days after intervention. Hand hygiene with or without facemasks seemed to reduce influenza transmission, but the differences compared with the control group were not significant. In 154 households in which interventions were implemented within 36 hours of symptom onset in the index patient, transmission of RT-PCR–confirmed infection seemed reduced, an effect attributable to fewer infections among participants using facemasks plus hand hygiene (adjusted odds ratio, 0.33 [95% CI, 0.13 to 0.87]). Adherence to interventions varied.

    Limitation: The delay from index patient symptom onset to intervention and variable adherence may have mitigated intervention effectiveness.

    Conclusion: Hand hygiene and facemasks seemed to prevent household transmission of influenza virus when implemented within 36 hours of index patient symptom onset. These findings suggest that nonpharmaceutical interventions are important for mitigation of pandemic and interpandemic influenza.

    Primary Funding Source: Centers for Disease Control and Prevention.

    Article and Author Information

    • Disclaimer: This work represents the views of the authors and not their institutions, including the Centers for Disease Control and Prevention.

    • Acknowledgment: The authors thank the physicians, nurses and staff of participating centers for facilitating recruitment and our dedicated team of health care workers who conducted the home visits.

    • Grant Support: By the Centers for Disease Control and Prevention, Atlanta, Georgia (grant 1 U01 CI000439-02). The Research Fund for the Control of Infectious Disease, Food and Health Bureau, Government of the Hong Kong SAR (grant 08070632); and the Area of Excellence Scheme of the Hong Kong University Grants Committee (grant AoE/M-12/06).

    • Potential Conflicts of Interest: None disclosed.

    • Reproducible Research Statement: Study protocol and data set: Available at www.hku.hk/bcowling/influenza/HK_NPI_study.htm. Statistical code: The R syntax to permit reproducible statistical analyses is available at www.hku.hk/bcowling/influenza/HK_NPI_study.htm.

    • Requests for Single Reprints: Benjamin J. Cowling, BSc, PhD, School of Public Health, The University of Hong Kong, Units 624-7, Core F, Cyberport 3, Pokfulam, Hong Kong; e-mail, bcowling{at}hku.hk.

    • Current Author Addresses: Drs. Cowling, Cheng, and Leung; Ms. Fang; Ms. Fung; Ms. Wai; and Mr. Sin: School of Public Health, The University of Hong Kong, Units 624-7, Core F, Cyberport 3, Pokfulam, Hong Kong.

    • Drs. Chan, Peiris, and Seto: Department of Microbiology, Queen Mary Hospital, Pokfulam, Hong Kong.

    • Drs. Yung and B.C.F. Chiu: Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong.

    • Dr. Chu: Sai Ying Pun General Outpatient Clinic, 134 Queen's Road West, Sai Ying Pun, Hong Kong.

    • Dr. P.W.Y. Lee: General Outpatient Clinic, St Paul's Hospital, 2 Eastern Hospital Road, Causeway Bay, Hong Kong.

    • Dr. M.C. Chiu: General Outpatient Clinic, St Teresa's Hospital, 327-Prince Edward Road, Kowloon, Hong Kong.

    • Dr. H.C. Lee: Out Patient Department, Hong Kong Baptist Hospital, 222 Waterloo Road, Kowloon, Hong Kong.

    • Dr. Uyeki: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333.

    • Dr. Houck: Seattle Quarantine Station, Division of Global Migration and Quarantine, Centers for Disease Control and Prevention, National Center for Preparedness, Detection and Control of Infectious Diseases, c/o U.S. Customs & Border Protection, 2580 South 156th Street, Building A, Room 101, Seattle, WA 98158.

    • Author Contributions: Conception and design: B.J. Cowling, C.K.Y. Cheng, W.H. Seto, R. Yung, D.W.S. Chu, T.M. Uyeki, P.M. Houck, J.S.M. Peiris, G.M. Leung.

    • Analysis and interpretation of the data: B.J. Cowling, K.H. Chan, V.J. Fang, C.K.Y. Cheng, R.O.P. Fung, T.M. Uyeki, J.S.M. Peiris, G.M. Leung.

    • Drafting of the article: B.J. Cowling, V.J. Fang, C.K.Y. Cheng, P.M. Houck, G.M. Leung.

    • Critical revision of the article for important intellectual content: V.J. Fang, C.K.Y. Cheng, W.H. Seto, R. Yung, B.C.F. Chiu, T.M. Uyeki, P.M. Houck, J.S.M. Peiris, G.M. Leung.

    • Final approval of the article: B.J. Cowling, V.J. Fang, C.K.Y. Cheng, D.W.S. Chu, B.C.F. Chiu, T.M. Uyeki, J.S.M. Peiris, G.M. Leung.

    • Provision of study materials or patients: C.K.Y. Cheng, R.O.P. Fung, W. Wai, D.W.S. Chu, P.W.Y. Lee, M.C. Chiu, G.M. Leung.

    • Statistical expertise: B.J. Cowling, V.J. Fang.

    • Obtaining of funding: B.J. Cowling, P.M. Houck, G.M. Leung.

    • Administrative, technical, or logistic support: K.H. Chan, V.J. Fang, C.K.Y. Cheng, R.O.P. Fung, W. Wai, J. Sin, P.W.Y. Lee, M.C. Chiu, H.C. Lee, T.M. Uyeki, P.M. Houck, G.M. Leung.

    • Collection and assembly of data: K.H. Chan, V.J. Fang, C.K.Y. Cheng, R.O.P. Fung, W. Wai, J. Sin, D.W.S. Chu, P.W.Y. Lee, G.M. Leung.

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    Summary for Patients

    • Summaries for Patients:The Effects of Hand Washing and Facemasks on Prevention of Influenza Infection Ann Intern Med October 6, 2009 151:I-18; doi:10.1059/0003-4819-151-7-200910060-00001
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