Hand Hygiene and Facemasks for Influenza Rejected at Home
Abstract & Commentary
By Mary Elina Ferris, MD, Clinical Associate Professor, University of Southern California. Dr. Ferris reports no financial relationship to this field of study.
Synopsis: Hand hygiene and facemasks used within 36 hours of patient symptom onset resulted in a small reduction of household transmission of influenza, but adherence to recommended practices was poor despite home-based education.
Source: Cowling BJ, et.al. Facemasks and hand hygiene to prevent influenza transmission in households: A cluster randomized trial. Ann Intern Med 2009;151:437-446.
Starting with 407 (of 2750 patients screened) influenza a or b cases confirmed by rapid testing in 45 Hong Kong outpatient clinics in 2008, three randomized study groups were created: 1) controls, 2) enhanced hand-hygiene instruction, and 3) hand hygiene plus facemask use. Educational intervention included all household members, and provided demonstrations in hand hygiene and mask use and disposal, along with actual provision of liquid soap, alcohol-based hand cleaners, and 50-75 masks for each person. Masks were recommended to be worn at all times except during eating and sleeping periods for both patient and family members for 7 days.
Family education was delivered by home visit generally within 12 hours, where baseline nasal and throat specimens were collected from all household members, who kept symptom diaries for the following 6 days. Follow-up home visits occurred approximately 3 and 6 days later with further collection of specimens and counting of remaining masks and weights of liquid soap and alcohol cleaners. After exclusions, 259 households with 794 household contacts completed the study.
The interventions did not result in overall statistically significant reductions in household transmission. The odds ratio for developing influenza was 0.73 for the hand-hygiene group and 0.89 for facemasks + hand hygiene (compared to 1.00 in control group). However, the odds improved if the interventions were utilized within 36 hours of patient symptom onset, to 0.54 for hand hygiene and 0.46 for facemasks + hand hygiene. Overall, 8% of household contacts in 19% of households developed laboratory-confirmed influenza during the follow-up period. An additional 191 (23%) contacts met clinical definitions for influenza without positive tests.
Commentary
Although this study is summarized as supporting early utilization of hand hygiene and facemasks, the results actually could not show a statistically significant reduction in household influenza among the study groups except when initiated within the first 36 hours (which may be before the patient is evaluated medically). Despite intense education and demonstration in the home, adherence was disappointing; only about half of the patients and even less of the household members used the facemasks. Hand hygiene "often or always" was reported by about 60%, which was verified in assessing the cleaning products remaining at the end of the study.
Airborne exposure to influenza may be the most hazardous,1 but our ability to protect ourselves is limited. The Institute of Medicine Committee on Respiratory Protection for Healthcare Workers in the Workplace Against Novel H1N1 Influenza A has just issued a new report emphasizing the inadequacies of the surgical mask, but better protection from the more tightly fitting N-95.2
It's nearly impossible to isolate which of the preventive measures were most responsible for reduced transmission, since the control group also practiced some hygiene without the extra educational intervention. The 7-day requirement for adherence was likely a burden for busy households, especially as the index case improved. This study is certainly timely and does provide unbiased results, being funded by public health agencies in Hong Kong and the United States without any commercial support. Although no dramatic impact was seen in promoting basic personal protective measures after illness onset, they still remain our main strategy to prevent infectious disease transmission at home if begun as soon as illness starts.
References
1. Brankston G, et al. Transmission of influenza A in human beings. Lancet Infect Dis 2007;7:257-265.
2. Shine KI, et al. Novel H1N1 influenza and respiratory protection for health care workers. N Engl J Med 2009 Sep 30; Epub ahead of print; doi: 10.1056/NEJM p0908437.
Hand hygiene and facemasks used within 36 hours of patient symptom onset resulted in a small reduction of household transmission of influenza, but adherence to recommended practices was poor despite home-based education.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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